For those who didn't know about this already, the artist is
Jonathan Coulton. He's a genius. For this song, I prefer the studio version, here:
Baby Got Back.
His other big web hits are
Code Monkey,
Re Your Brains, and
First of May. There are fan-made videos for all of them as well, just search.
I can also highly recommend:
Stroller Town and
Chiron Beta Prime.