AFAIK you could get serious burns  even when antenna was not powered any more. In this case it works just like huge receiving antenna, getting kilowatts of RF energy directly from atmosphere. Before the thunderstorm ropes holding the antenna literally glowed due to corona discharge effect.
A few years ago both antennas were demolished 
 http://vk.cc/4LQeGa (wiki, Ukrainian)
Popular Science once ran an article that showed how to build an electrostatic motor that ran off the atmospheric electricity you could get with something like a wire used as a kite string.
Once you were on the tower you wouldn't notice anything. You would have to get between the ungrounded tower and ground.
If I lived close enough I'd be trying to work out some kind of trickle charger for phones.
I can't compare RF burns to burns caused by electrical current, except to say that electrical current will follow some path of least resistance while RF energy will heat flesh in a pattern corresponding to the field of the radiator and the impedance of the whatever matter absorbs it, so these types of burns will have different patterns.
(Or so I'm told. So far I've been able to avoid experiencing one myself.)
I was an embedded engineer at an RF company and it sort of comes with the territory. We had technicians who had lasted 4+ decades in RF (same company, actually) with scars to show for it. Same story, mostly on their fingers from accidentally hitting hot spots.
I was burned by ~300W in the specific cases I mentioned. I think it probably classifies as second-degree burns and (because I was young and dumb) I never did anything to help prevent scarring or heal the tissue besides basic first-aid. Safety first, everything else is secondary.
Actually, now that I think about it, it'd actually be most similar to how a microwave heats meat, wouldn't it? Microwaves being within the RF part of the EM spectrum and all. (Though not quite the same, given the lack of dipole interaction with water molecules outside of the particular part of the spectrum microwaves sit on.)
I was told this story by my grandmother to prevent me from watching food cook in the microwave. That and cataracts, which can also be caused by heating up things that shouldn't be heated.
The turntable in my microwave failed when I heated up a frozen pizza, and the result was part of it was burned, and part of it was still frozen.
Because of how AM works, you can actually hear what's being transmitted by causing an electrical arc. It's the same concept of hearing a "buzz" from high voltage power lines, except in a controlled fashion to produce sound.
If you have an old CRT, you might be able to achieve a similar effect with Tempest for Eliza.
A search for "singing Tesla coil" will turn up many more.
A modest proposal: "What 50 kilowatts of RF power sounds like through a jumper cable"
And you still got it wrong.
I don't think it's a capitalisation problem; when using 'Watt' as a name, e.g. James Watt, you need to capitalise. But the unit is 'watt', with a lower-case 'w'. The symbol is an uppercase W. Reference: Table 3, in "NIST Special Publication 330: The international System of Units (SI)", Taylor et al (2008).
Nor do I think there's a problem with confusing energy and power, as there currently is in the original title.
So, what's the problem? Jaquesm's "And you still got it wrong" comment is unhelpful because it doesn't identify a specific problem. Maybe he feels that the sound doesn't actually come from the cable. Or maybe the cable isn't carrying 50 kW. I don't know. Maybe there is an obvious problem I'm missing.
Whether that's what jacquesm is referring to or not, idk.
Since this is AM you end up with intelligable sound (for an FM station this trick wouldn't work).
Not the prettiest thing, but there you have it.
The guaranteed way to do this is just to grab and use youtube-dl. It supports almost everything nowadays, and it's where all the updates and maintenance goes. Passing the OP URL got me a copy of the video perfectly.
Why were they shorting out the tower? (What was the purpose of the cable)
What are those rubber things?
What would happen to a bird that landed on the tower (not grounded)
What about a large metal helicopter (if it didn't crash)?
Since the tower is metal, it will inherently start to resonate to the transmissive power. (The same effect can be seen when you touch a phono connector to an active amplifier, the 50/60Hz hum can be heard because you are absorbing some of the mains voltage energy radiated around you.)
When you transmit, any metallic object around the antenna can affect the impedance of the system. Usually the system is tuned with respect to the antenna and mast structure. At 50kW the antenna mast structure is resonated so hard by the antenna that high RF induction is present in the mast structure itself. Mast maintenance is normally done with the transmitter turned down or off entirely. Since this is a broadcast mast, this is not so easy. Grounding the mast structure may imbalance the tuning slightly but not enough to be of a concern with damaging the PA's. But the safety of maintenance engineers is a mandatory requirement.
Why not ground the mast anyway?
If you are inductively resonating a gigantic mast, you are also assisting in improving the gain of the irradiated signal. Hence why in the video the bottom of the mast has a black block of plastic/rubber.
I wasn't sure about the device they were shorting so I asked the chief engineer for several large radio stations in the area.
That device is a lighting transformer  -- it allows AC power to be coupled to the tower, to power the lights, without a direct connection, which would severely impact the tower's ability to radiate RF energy. The two little balls is called a lightning gap, it gives lightning a path to ground, other than the connection to the transmitter, since the tower itself is not grounded.
 http://www.sonifex.com.au/?media_dl=3300 (PDF)
Right. At those low frequencies, yeah, you need a pretty huge chunk of metal to radiate efficiently.
Alternatively, could this be an unpowered antenna that is picking up signal from a nearby powered one?
I'm pretty sure this is what's happening. From past experience with high voltage arcs (admittedly at 60hz, not ~1 MHz), I don't think we're seeing more than a few hundred watts of power in that arc. Also, if this tower was actually the one transmitting that signal (presumably 50kW is the transmitter power) they'd shut it off or switch to a different antenna for maintenance on this one. If you shorted the output of the transmitter at the point where it's normally driving a resonant load, the best possible case is that it would trigger some kind of automatic shutdown on the final amplifier.
How do you think the human standing right next to the tower is not getting fried?
Humans climb live radio towers routinely.
The tissue absorption of RF energy at common AM station frequencies(below 2mhz) is negligible. Maximum absorption happens around the frequencies commonly used by FM stations (about 100mhz)
I have climbed near an live FM antenna. You can feel the heat(well, radiation, converted to heat by your body tissue) from the antenna, it feels like a heat lamp. Your eyes are the most sensitive parts as they have the least ability to dissipate excess heat. The old rule-of-thumb is, if your eyes are watering, you're too close to the antenna. But like most things 'the way they use to do it' -- by that point damage is already being done. Cataracts are one of the first signs of RF induced tissue damage.
It would take many thousands watts, transmitted at frequencies well above common AM frequencies to cause any sort of instant damage. I have never seen a field of dead birds near even major FM stations broadcasting with 50kw+ power.
I made a point of swishing the rotor side-to-side a couple of degrees after I figured out where the dead sparrows came from. That caused them to fly off and once the transmitter was on they'd stay away from the antenna.
The 'drum like cover' is called a radome, and it's primary purpose is to reduce the wind loading of the microwave dish. It also serves to protect the usually sensitive feedhorn inside the dish, keep out bird nests, ice, water, etc...
The common cause of bird deaths around radio towers is collision, not RF energy. In Florida it is very common to see osprey nests build on/in/around towers. Microwave dishes are a common location because they provide a large horizontal surface to support the nest. See Wikipedia article 'Towerkill'
The physics of electricity propagation in a powerline circuit is fundamentally the same as the propagation of FM radio waves, or even the beam from a flashlight. All of these examples involve electromagnetic energy propagating at the speed of light. So why do we need wires for powerlines, but not for propagating radio signals or light beams?
The principle is that light (in a vacuum at least) travels at a constant but non-infinite velocity, c. Hence, the electrical wiggle received at an observer's location now i.e; (x,t), has been caused by some earlier wiggle conducted by the source (x',t') such that the t-t'=(x-x')/c. We should expect that the effect of this 'time delay' is more profound if the source is wiggling faster in time.
A more specific way to state this is that the electromagnetic power radiated into free space by a dipole increases as the square of the dipole moment and the fourth power of the frequency. Now compare a powerline (60 cycles/sec), with FM radio (100 Million cycles/sec), and with the light from a flashlight (500 Trillion cycles/sec). That's why even atomic dipoles can produce intense visible light, while it would take a very very large dipole to radiate a similar intensity at 60 cycles.
Feynman Lectures Vol.II is absolutely the best reference to learn this stuff.
That is not to say that a bird needs to make contact with two wires on a utility line, in order to suffer harm. If the line voltage is high enough (e.g; 110,000 Volts, as in high-tension power transmission), an electrical corona would form around the line from electrostatic effects. The corona is actually ionized air indicating the high electrostatic field strengths in the region, it can emit a bluish glow and growl at 60 cycles. Birds can no doubt sense this corona & stay away.
So can humans, it's a crackling sound.
If you are near an AM station, you can make a radio with just a earphone(now called ear bud?), a diode, and a piece of wire.
You will pick up all nearby stations, but one will likely be stronger/closer than the rest, so you would hear that one.
A slight improvement of that is the 'crystal radio' that adds the ability to tune to a certain station. 
It is common for people living near AM stations to hear the radio signal induced into their house/business wiring. It's a common problem with landline telephones near these stations, you can hear the radio in the phone while you're trying to use it. Intercom systems are also vulnerable.
You've probably also heard this from time to time when someone with an illegal CB amplifier uses their radio near a business with an intercom system. It will typically briefly bleed into the intercom system, with everyone looking around trying to figure out where that noise came from.
This may be common only in the south, I'm not sure how prolific CB radios are throughout the country.
Electronics was one of my hobbies. Most of the noise in my circuits was that damned time signal. I could pick it up with just about any length of wire and anything that would act as a diode. A transistor. A pin on a chip -- I had a DRAM coughing up "At the tone, the time will be..." once.
At least I usually knew what time it was.
BEEEP dooo dooo dooo dooo
There used to be stories, not entirely urban legend, of people who lived close to AM towers hearing the station in the wiring of their home, or in their dental appliances. Not impossible, considering that many AM stations broadcast with 50kW of power (like the one in this video) and can be received across a large swath of the country.
To give you an idea of how powerful that is, take a look at their coverage map: http://i.imgur.com/Aigz1Zh.jpg
The back story is kind of interesting. It was run by Powel Crosley - a sort of 1930's version of Elon Musk. Advertising revenues from the station were so successful he applied to increase the limit from 500kW to 750kW(!).
It's a big deal in the ham community, but I only learnt latter that while US stations were limited to 50kW - other parts of the world didn't have such restrictions. Parts of the Middle East have 2,000kW stations. 
You can get a full download on the Crosley WLW station in this video: https://www.youtube.com/watch?v=CbHjcwIoTiY
It's been dismantled, but I can imagine the number of ghost stories that it spawned. Just sitting in your house, and then you faintly hear a man speaking German...
I never heard the broadcasts through metal objects in the house either, but maybe they scaled back the power in the time I grew up there. Never heard any VoA broadcasts either.
It seemed that the signal path into the speakers was through the input wire (rather than, say, the power cable or the wires between the amplifier and the cone). From what I understand from my undergraduate analog signals course I'm suspicious of the signal actually coming from the transmission tower itself, unless the speakers had just the right configuration to act as a simple diode-rectifier envelope receiver (terminology likely to be incorrect), which I would think of as unlikely for an FM signal.
It may be that the signal came from some other path related to the relaying of the signal from the studio (~1 mi away) to the tower, but I don't know enough about the specifics of the radio station's configuration to say more.
I think I did eventually pin down which station they were picking up, but I've forgotten now. Interestingly, since I've moved to Switzerland, it's stopped. Maybe the signals don't get through Swiss customs.
That said, I didn't live 300m from 100kw...
Reminds me of a Gilligan's Island episode, Hi Fi Gilligan: https://www.youtube.com/watch?v=3x1XHv0sxro
(edit: I'm way wrong on the piano. arjie's correct about the backing track)
which I will remove at some point
The numbers you quote (1W [not dBm!] is 7.1V) make me believe that you assume an impedance of 50Ω.
In : math.sqrt(1*50) # P[in W] * R[in Ohm]
Out: 7.0710678118654755 # U[in V]
In : math.sqrt(50e3*50) # P[in W] * R[in Ohm]
Out: 1581.1388300841897 # U[in V]
Note, though, that with large installations it is likely that there are a few individually tuned feeds. And the cable might not be a 50 Ohm cable, but maybe a chicken ladder (two strands separated by fixed spacers), large-area waveguide, ...
Meanwhile, there are plenty of things Facebook could have done to be annoying, but they didn't do those things. I don't have an account. The link loaded fine. What's there to complain about? The web worked like the web.
I got the "you must login to continue" prompt on Facebook, but managed to save the video and upload as a good old static mp4...
the video is low quality, as is the version on FB.
Watts = power (how fast you do the work)