I love every scene with the Bumble in Rudolph, and when Frosty first comes to life. Santa Claus is Coming to Town is my favourite Christmas movie but I can't think of a particular moment from it. I also love the Ghost of Christmas Present from The Muppet's Christmas Carol. "You're a little absent-minded, spirit." "No, I'm a large absent-minded spirit!" Bwahaha.
Whoops -lack of comprehension: My favorite has got to be A Christmas Story when Santa kicks Ralphie in the face.