It's a genuinely brilliant gag, not just because the concept of a Tetris movie is funny, but because these guys have nailed the precise approach Hollywood would take. From the portentous narration ("Life is just... blocks... trying to fit together to make lines... and that's... who we are."), to the cheesy futurism, to the hilarious reconceptualization of Tetris as an extreme sport, to the scene where an impressive new competitor takes off his helmet to reveal that he is a she, it's perfect, and totally familiar. Not to mention the fact that it gets the trailer format down pat: the text inexplicably appearing as Russian before turning into English (well, maybe not inexplicably, since the game originated in Russia), the generic rock soundtrack, the triumphant last Tetris drop followed by the title screen -- it's an almost transcendent parody.
There's some other funny stuff on the site -- including the Iron Man trailer redubbed into Iron Ma'am -- but I haven't found anything as good as this.
[hat tip: Filmwad]