The soundtrack to recently released Wii title Super Mario Galaxy 2 has been uploaded as individual movie files to YouTube by an account under the name of composer MahitoYokota. 

Seeing as the page has not been taken down, even after being linked to by various press sites, it seems likely that the media experiment is a surprise advertising tactic by Nintendo, as opposed to an anonymous fan tribute.

Over forty tracks from the game can be heard on the YouTube channel, which is now close to reaching 1,000 followers.  Nintendo has traditionally maintained a cautious attitude toward music releases, tending not to publish soundtrack albums or encourage publicity surrounding the work of many of their in-house composers. The YouTube experiment may prove to be a successful new approach by the company to provide greater exposure to their game scores.

Nobuooo Videogame Music News