Advertisers also will pay a lot higher rates for those long-form ads.
Because someone who’ll watch a 30-minute video is HIGHLY ENGAGED. They are far more likely to become a customer than someone who just watches a two-minute entertaining video.
I think that “video” is too broad for this topic. To consider only educational and entertainment videos, I see a huge difference. I don’t believe that entertainment videos will become longer. Entertainment is a sort of thing that doesn’t have to go either deep or long. Thus it doesn’t need large chunks of time. Educational video is a totally other story. While there are many “howto” type of videos, many topics require more than 5 minutes to explain. Take Google Tech Talks for example. They are pretty popular and each one takes about an hour.
There is also this factor of production costs. It’s much harder to create 60 minutes of high quality (and I don’t mean pixels or bytes) video material, than 10 minutes. Or 5. Filmmakers know that. And the audience knows that. While less and less filmmakers will risk it, and more and more of those who do risk it will produce crapy long videos, the audience will learn the benefit of a short video and will be more inclined into choosing shorter formats.
However, since I am not at all involved in any video production or distrubtion, I might be totally wrong on this. Judging purely from my own experience. And my own experience mostly comes from YouTube and Google Video.