Alex Iskold came up with an interesting post on ReadWriteWeb recently. He uses some evidence from recent Conferences and eventually says "because video was not possible before, the web was dominated by text. Now that video cameras and broadband are cheap, information that is better served by video is getting converted. As a result, YouTube is now the second largest search engine, and traffic is through the roof." So video is on the increase on the Web and many kids are video natives.
I would add that YouTube is a phenomenal teaching resource whic we librarians could all use much more. The challenge is to keep up with what is out there.