Viral Marketing Kermit Duets with Tiffany Thornton In Holiday Music Video Dan Koelsch, December 24, 2010 Usually the YouTube videos from The Muppets are clever and entertaining, but it seems like they missed the mark in their latest video, which celebrates the holiday season. In it, Kermit the Frog sings a Christmas duet with Disney pop star Tiffany Thornton titled “I Believe”. This cross promotion within…