Either someone's reeeaaaal good in making fake videos, or Namco is hiding something they didn't want us players to see (but obviously, someone managed to leak it to the Net).
Forgive me if I would be a bit of a nutty detective for a fraction of your time and explain my theories.
Around 01:31, they were to make a jump. What caught my attention was two things: 1) that scene was noticeably lighter than the rest of the scenes in the song; and; 2) Before the jump, the girls were lined up as Haruka-Yukiho-Mami-Miki-Ritsuko. But when they would do the jump, they're lined up as Ritsuko-Haruka-Mami-Miki-Yukiho. And afterwards, they went back to Haruka-Yukiho-Mami-Miki-Ritsuko. We didn't see them go to the respective positions and did it before a blink of an eye. What the hell?
Those facts can support the two theories I just posted. For the first, if I'm right about the game being mod-able, he could've set everything up to make it look like the real deal. That person may have intentionally left that scene as it is to see if we would buy it. Also, there are many ways to come up with the voices for the song, such as splicing of previous voices, or finding people who could mimic the voices of the idols we saw (Note that the idols appearing here were some of the high-pitched voices in-game, and one incredibly good mimicker is all that's needed).
For the second, however, perhaps this was intended to be one of the new available-from-the-start songs the players would have. But for some reason they (programmers) couldn't fix a glitch in the dance, which is on that step I've mentioned. So they decided to bury it within the game, in hopes no one skilled enough can find it. Until today......
I have a third theory, but I'm not gonna mention it because it's highly unlikely (and I know some of you will post, dismissing me as a/an <insert offensive term here> and an idiot who barely knows a thing about how the game works (which I'll admit, I am, so you get that insignificant one point now)). It also relies on that scene, but not as seriously as those two.