Just saw this on Kotaku:

http://kotaku.com/387830/this-hands+free-super-mario-world-level-plays-sweet-sweet-music

Truly awesome!

btw does anybody happen to know where I could find an MP3 of this without the Mario World sound effects?

Nico Nico Douga (http://www.megaupload.com/?d=GL1EYUGZ)
Contains the version used in the video you posted and 2 vocal versions.

Really impressive !!!