I call hoax!
I think this is a complete hoax. I think the video that turned up on YouTube today showing a very bizarre bit of alleged Halo 4 game play footage recorded on VHS tape is an attempt at making a viral video by someone at Microsoft or the Halo 4 developer. The video shows someone playing horrible music while watching a TV sitting on a hay bale that shows video of Halo 4.
The game footage is on a VHS tape that shows Star Trek Deep Space 9 on the label. You have to watch the video to see how truly bizarre it is, there's a bear sitting at a picnic table that has a human face.