I have a feeling I'll be adding to this list -

Harpers Hall from California

This is the shortest, but perhaps the most instructive - from Sharlene Wallace - don't miss it! 

and this from Trisha Daniell "You might enjoy this mash-up of Handel's Messiah with 31 different carols mixed in!"

and this - https://www.youtube.com/watch?v=JLeCLRK8Ws8 awesome dancing