My favorite recent find:

Gwen Verdon on The Ed Sullivan Show:
Original: http://www.youtube.com/watch?v=PFhXyns6vzE
Fosse “Walk it Out”: http://www.youtube.com/watch?v=NIGbhPLZmjY

Surprisingly, the Fosse version is remarkable and I like it better than the original - looks choreographed.

-- John

Edit - Wow pulled down already! Disregard. But to not waste the thread, this is one of the funniest moments in movie history - much to the chagrin of both actors: http://www.youtube.com/watch?v=oEBHYJli6gw