Where bad choices make good stories
I bet I watched that like 10 times, and it looks like a blanket or tarp or something like that, and it's being pulled by someone towards the top right of the screen, whom you can't see. But if you just look for motion, there is none on the yellow to the left, only to the right, and while the guy is walking in front of it, look up some to the right.(Not that I don't love to find anything to blame on someone..)
Yup, I saw it also. It is a bloody blanket that is pulled by someone just off screen right.