I'm willing to hedge my bet on poor video resolution, but I didn't see anything in the videos which looked obviously like someone just unloaded a couple hundred rounds in a confined space. Esp on the scene on the concrete. What is obviously missing is the clinking sound of brass hitting the ground after the last shot. Usually about 1-1.5 secs for ejected cartridge to hit the sounds.

Again, there are a lot of variables involved, but you would have seen the empty shells bouncing around. Also, ARs eject at 90 degrees. Those shells looked to eject forward at 45 degrees. weird.