"The Professor" has some interesting videos about the pagan origins of Christmas and why he, as a non-believer, celebrates Christmas. He asks,
"Why do Christians use the trappings of a pagan festival to celebrate the birth of Jesus when the Bible commands believers to avoid such things?"
Links referenced in the 2nd video appear at the end of this post.
Links in the second video:
TogetherForPeace's video "Fighting for Christmas" (This one includes some good history about the celebration of Christmas.)
Professor's video "Unyielding despair, you say?"
Professor's video "Why are you an atheist?"