I have to agree, if MS has not demanded it taken down from Youtube then it's for sure a market ploy.
You have to watch the video to get how truly bizarre it really is, which you can see above. However, just to offer a bit of a teaser - it involves a VHS tape of Star Trek Deep Space 9, a bear at a picnic table with a human face, horrible NSFW music, and an old CRT TV sitting on a hay bale. Frankly, I don’t get it either.
The individual who posted the videos goes by the name of Skid Kid, and notably this is the only video posted to the account - which screams hoax loud and clear. Then again, there is the distinct possibility that someone at Halo HQ is trying to make a viral video to drum up some buzz for the long-awaited game.
The camera work is some of the shakiest we've seen on a leak in a while, but it does appear to show some Halo footage we haven't seen. As Destructoid points out, the game play footage is certainly not Halo or Halo: Reach. (Note: Microsoft is currently conducting internal beta tests for Halo 4, yet and has no plans for multiplayer beta of the game).
The video is still up and has managed to garner over 100,000 views. Clearly, Microsoft and Halo 4 developer 343 Industries aren't in a big hurry to pull it down. If this turns out to be a viral marketing stunt, which I suspect it is, whoever came up with it needs a random drug test because you'd have to be fried on one thing or another to come up with a video this bizarre."