If you've ever been interested in checking out videos about artists like Matthew Barney that aren't limited to the 2 minute run-time of the art 21 clips, check out UbuWeb.
About the site:

UbuWeb is a completely independent resource dedicated to all strains of the avant-garde, ethnopoetics, and outsider arts.

All materials on UbuWeb are being made available for noncommercial and educational use only. All rights belong to the author(s).

It has a great collection of videos and sounds and would be perfect for educational purposes.