The excellent Ubu Web is screening Derek Bailey's On The Edge, first shown on Channel 4. Well worth a couple of hours of your time.
http://www.ubu.com/
http://www.ubu.com/film/bailey.html
The series arose from his seminal book on improvisation.
http://www.amazon.com/Improvisation-.../dp/0306805286
I saw him perform solo once many years ago, me and about 5 other people!
He was a genius.