I just wonder if its fake or real.
According to the video its in Lower Manhattan (South of Wall Street around Hanover Square / Old Slip) area.
If its real thats a big cloud.
I just went to the YouTube link because I didn't see it at first, but in the comments section of the YouTube page someone says that the cloud can be
seen in the Naudet brothers film as well. I wonder if that was one of the exploding vans.