Ok, I get it. The song was called one thing but the video title put "holiday" into said title in order to get more hits. In which case the question becomes, "If it was made for YouTube anyway, why didn't they just call the song & video the same thing?"
Speculation is pointless. This is YouTube we're dealing with, which is all about getting the most hits, & I can't watch every one of these damn things all the way through for title confirmation. I've got Xmas shows to make.
Oh, wait. That's what I'm doing now. Better get back to it.