Wouldn't it be great if you could get the original video files back out of YouTube? Wouldn't it be great if you could just upload videos to YouTube and have them automatically appear in iTunes, correctly transcoded as needed?
Yes, I was as surprised as you when I went poking around the YouTube developer section and found no methods to get back the original video files or to do any of these other things I wish for.
I still like Revver's "bolt ads to your videos" business model, and AudioBlog is still my choice for the most flexible commercial service to easily input/host/etc. all your audio and video service (including direct-to-iTunes support).
But where are people putting videos in order to get an audience? YouTube, of course. Let the chorus of "YouTube sucks" begins...until someone else manages to make something that is as popular.