Technically speaking, the piece is called "Carol of the Bells," not "Ringing of the Bells" as the YouTube video puts it, but if you've got the Muppets performing it, you're probably not looking for technical accuracy.
Funnily enough, before seeing it, I probably could've told you that it'd be performed by the Swedish Chef, Beeker, and Animal -- the three Muppets whose vocabulary range is limited at best.
The Muppets - "Ringing of the Bells" [YouTube]
