The majority of TV programming is designed to constantly, subconsciously capture your eyes and ears. The picture changes every couple of seconds giving your eyes something new to process. The sounds (music, noises, and voice) tease you to watch what's going to happen next. This is why having a TV on "as background noise" while you try to do something else usually results in you watching more TV than getting things done.
A video on the web usually has the camera focused on one person and the screen doesn't completely change too often (if at all). Also, the speaking isn't exaggerated in any way to entice you to pay further attention. Therefore, it doesn't measure up to the levels of excitement/entertainment that your brain is already used to from TV.
That's funny -- my current pattern is to watch TV on one monitor, and then do stuff on the web (like read HN) as background noise on the other. The result is that I get more things done than watching TV.
If I watch TV, I watch it for entertainment. PG is a smart guy, but I'd rather watch Seinfeld reruns for entertainment, and watch PG to learn something new. At that point, though, I'd rather simply read what he has to say at my own pace, rather than wait around to hear him say it.
Part of it is that watching a video takes the control of pace away from the consumer of that information. Whereas if you can read it, you can set the pace. Read it fast, read it slow, re-read important parts, highlight something and right-click google it, etc. Can't do all that with video.
Additionally, some people are aural learners, but others are visual. The latter generally have better synthesis and recall of things they read than things they hear. Such people likely prefer reading summaries than watching the video.
I wasn't thinking transcription. I was rather thinking about better navigation or focus on the interesting parts of a video. For instance:
idea #1: play video at 2X (or 1.5X speeed) with no pitch modification, so quickly go through most content. When I focus on the video frame, slow down to normal speed. Maybe have an obvious "rewind 30 seconds" like TiVo, so I can re-hear what sounds interesting
idea #2: tag the video timeline from other users commenting on specific times of the video (I have seen this on some video sites). That helps navigate faster and "move around" a video.
The main problem I see with the video format? Think of DVD vs. VCR. It's about rewinding and direct access. A video player online is just a long line, you get lost very easily. Somehow, you don't get lost navigating pages of text. Haven't you ever been frustrated that you couldn't find back something you just saw in a video? And I don't mean search by keyword...
I've found that listening to videos on BloggingHeads.tv at 1.4x speed works just great, and really improves the user experience -- and I never have to slow down or rewind, either. All video sites with people talking should have this as an option.