You can even try it out now on Safari Technology Preview: https://webkit.org/blog/7627/safari-technology-preview-32/
This is absolutely huge. Many, many services that could once only be provided at a premium fee or by large to massive companies like Skype or Google can now be offered for free by small start-ups without having to worry about "this page was designed to be viewed in [preferred browser] version [foo] or higher" hassles.
Well, I have been figuratively waiting for it for 6 years.
Alternatively they’d have to add VP8 support in their chips and one suspects they would be unwilling to spend silicon on that which could otherwise be used for whatever witchcraft their silicon designers are whipping up.
I’d grant that as a valid technical reason for limited video codec support. Silicon and battery are at a premium.
HLS has no such problems which makes it the better choice.
And Columbia University is in that patent trolls list. Disgusting.
Going through that site, I found their attempt to leech on VC-1: http://www.mpegla.com/main/programs/VC1/Documents/vc-1-att1....
And they list Microsoft there, which is strange, since MS are part of Alliance for Open Media which is an antithesis of this trolling cartel. Either MS are sitting on both chairs, or MPEGLA are trying to fool everyone.
Apple was doing video  long before Firefox and the web were a thing; perhaps it's Mozilla that needs to get with the times and industry standards.
Here's an article on JavsScript based HLS from a couple of years ago:
Web browser considerations aren't relevant on iOS because Apple forbids alternative browser engines. Firefox on iOS is not Firefox because Apple doesn't allow it to use Firefox's JS runtime or Firefox's render engine. As a result there isn't any true browser competition on the iOS platform, which is a shame.
Personally, I want to run full, real Firefox on my iPhone. It's a low quality move from Apple that they stop me doing that.
I'm sure a lot of them do, but it's also true that there are a lot of Mac laptops out there which will be upgraded to High Sierra that don't have hardware HEVC acceleration.
Both HEVC and H.264 require the patent holders to be paid in order to be allowed on either a device or content.
One obvious technical issue is that, as far as we know, there's no VP8 decoding hardware in any of Apple's products; implementing VP8 decoding in software might be more of a power drain than Apple wanted.
But what I found interesting in the WWDC session you linked to was that a lot of Apple products don't have hardware HEVC decode and\or hardware HEVC encode support. Apple has implemented software HEVC decoding and encoding in a lot of places. From that perspective, adding support for VP8 and VP9 wouldn't be much different.
If I tick "Remove Legacy WebRTC API", and retry, they all fail until it gets stuck with no message on "Udp enabled".