You know, there's also the fact to consider that, well....if the video was leaked, the DLC (well, at least, the song) is complete...I wouldn't find it too odd for inner members of NBGI to be playing it in their games or something.
(I mean...it -did- have to be leaked by or through someone in NBGI...if a fan already had it in his clutches, I'm sure we'd be seeing at least higher quality video, if not more than one.)
Even in that picture, I mean...look. The unit's name is "Namco Angel"/ ナムコエンジェル...which, is pretty common in S4U videos with people who don't want to name their unit, but generally, in the actual gameplay, you'd take the time to name them...not that it makes or breaks the argument. Heck, there are a lot of possibilities with that screenshot. It could, in fact, just be a screenshot displayed on a big TV. We don't know.
But I think it's better to assume things like that are legit, rather than hacked. I really don't think NBGI would make their main source of fan-wallet suffering easy to steal.