I agree with ebc, that trancey phasing effect does not work with the song. Musically it's a nice holiday season song, but there's stuff that just doesn't fit.
^ I think the vocal coloring seem pretty correct to me, except I think you're right about the "taktak teoreo beoriji" part. And I can't really tell with the La La La stuff, but it sounds like more than two people, I think sunny or jessica might be there, but that could just be the effects.