Valve hasn't been great at keeping secrets recently. Left 4 Dead 2 was leaked a few days early, the "Meet the..." videos have been made public before they wanted, and now a new Left 4 Dead 2 cinematic trailer is available for download. It's not the greatest quality, and the audio is for shit, but hey, it's more L4D! Not only that, but it shows some new stuff that might or might not actually be in the game. Hell, if I didn't know better, I'd say that this game had some sort of a story!
The video shows off clips from "Hard Rain" and "Dead Center," two of the campaigns, and all of the new enemies. It seems to focus on Ellis, and shows the mechanic getting the shit kicked out of him by just about everything. He's jumped on by the Jocky, spit on by the Spitter, and smashed into stuff by the Charger, all before nearly being eaten alive by the Licker Smoker. Is this the beginning of a "Meet the Survivors" series? Maybe.

More likely than not it's an unlockable video or introduction to the game. Either way it's worth watching, and should convince any boycotters to shut up and throw down their cash.