Interesting topic to think about, thanks for posting this Lee.
There are parallels in other online media. For instance, some of my favorite blogs are tumbler sites like Daring Fireball which are masters of the 100 word (or less posts). And others, like the Accidental Economist, regularly turn out 5,000 word essays.
Similarly, I listen to an hour long podcast on my commute to work, or a 10 minute NPR story while walking to lunch.
I guess what that leads me to believe is there is room for a ‘both and’ —both short and long form videos. And I think your insight is spot on – for the right condition, there is an audience who wants long form, in depth info. For general awareness, short form may cast a wider net.