SilverWook said:

There are tons of fake Episode 7 trailers and such on youtube, so why would Disney want a takedown if it's fake? Unless it's a clever marketing campaign.

I've found there's really no logic behind why some videos are removed and others remain. I've had Disney related videos removed while others exactly like it remain and continue to remain, even Star Wars videos. I've haven't come across anyone who has actually seen the video, just the screenshots. I'm sure security is pretty tight and I can't imagine nobody would notice a person standing in front of a monitor (for at least a few minutes) recording this footage with their phone. It's fun to speculate, nonetheless.