[kalid]

Well said. Where's the video version of Wikipedia? Hacker news/reddit?

As a teaching tool, video doesn't lend itself to iterative refinement or discussion. It's an excellent audiovisual experience, but also a bet that the content is best delivered in a read-only format. (Practically, you can't update a video, only redo it -- presumably at full cost.)

I see video as a supplement to lesson formats that can be improved over time (text, or whatever medium comes next).