Quality online video of performance dance continues pop up all over the place - check out Motion Bank - a notation database for dance.  

A 4 year long project by the Forsythe Company, a piece of digital "sheet music" is created directly from choreography.  William Forsythe's first online project is Synchronous Objects, breaking down his piece One Flat Thing, reproduced.

Explore the site at: http://motionbank.org/