So the fact that Namco keeps taking this down rabidly means that it pretty much is official, right? There are some weird parts though. Like around 1:50. No other songs have the camera work so whoever is singing is blocked off by another idol's head. I don't care if it's fake or not, the choreography is awesome and the song will be stuck in my head for the rest of the day.
I thought that was weird, as well, though...having that "hurr my face is blocking the camera :B" moment can happen pretty easily (at least, in L4U; try setting up your cameras all pretty and then the game chooses a bad angle and you have a fuzzy idol blocking the view), though I think we can all generally agree that the choices made in this PV aren't necessarily the best XD
I really wouldn't think it's a fabricated video :s MMD will never look this good, and, well...just look at it. Why would someone put that much time and effort into trying to make people think there's a DLC song when there isn't? Painstakingly carving the models to look exactly like the ones in game, programming lighting, writing lyrics and BGM for the song...underneath those Live performances is a lot of work XD I don't think anyone can just do that for giggles.
I really liked the coreography more than the song itself at first, though the song is starting to get addicting (heck, I'm listening to it right now XD)
EDIT: I just noticed in the pic of the cover that Takagi is going "Uuuu" NO YOU CAN NOT SAY THAT ONLY YAYOI CAN YOU ARE NOT A LITTLE LOLI STOP
Wait, where?? XD