bike punx sk8 video, out of LA/SF?
http://michaelmartin.com/blog/photos/track_video.html (been posted a lot)

indoor artistic cycling:
http://www.hk-icycling.net/movie/erl4men.mpg (orig. posted by cookiepuss)
http://www.city.kaseda.kagoshima.jp/...g2000_english/ (vids at bottom of page)

mountain unicycling (aka 'muni'):
http://www.xtremeride.net/webisodes/vol17/uni.mov (orig. posted by dirtycookie)
http://www.krisholm.com/multimedia/ (dvd's for sale)
http://uniplex.libsyn.com/rss (video podcast via uniplex.org)