Ok so just from watching that video, you ABSOLUTELY cannot tell that they are carrying camera instead of weapons. One of them had something that was really long, just like an RPG, another had something in his hand that looked, to me, exactly like a small AK-47, Then one was ducking behind a corner and sticking his camera around the corner like it was a gun and he was shooting around the corner.

Wrong place, wrong time. Simple as that. Sucks they got killed, but shit happens.