This is kinda hard to rate/review, since it doesn't have any animation whatsoever.
(Well, the droids dancing and rebels running hardly counts.)
I can't help but to compare this to Lech's "Twelve Pains of Christmas." Yes, it was released back in 2004, but it was recently-ish bumped.
Lech's not only has animation in for all of the "days/pains," but different animation each time through.
That way, it encourages people to watch the whole thing instead of simply skipping to day twelve and watching everything just the once. Yours has mostly slides, and the same slides every time. There's no reason to watch all twelve days develop. The song itself (I'm talking about the "Twelve days" format, not just your version.) can get boring relatively quickly, so pair that with the same slides over and over, and things go south after about day four.
The only animation that I saw in yours was some VERY choppy, and obviously poorly looped footage. Looping clips isn't a problem, but only it the viewers can't tell that it's looped. If you had a rebel running from far off-screen, across the set, and off-screen on the other side, then not only would it be less noticeable looping, but the clip would be longer each time and only repeat a few times. (As opposed to the break-neck pace of the current stuff.)
Here are two final thoughts, and a question:
#1, If you must use slides, make the sets really detailed and interesting.
#2, It's obvious that the singers have a slightly different tune going on in their heads. It wouldn't take much to prevent that.
And what do trolls have to do with LSW?