Looked like his leg hit in to the rock pretty hard.
whilst climbing/belaying is a situation where you have to trust someone, thought this was an unrealistic portrayal, you would typically not use the (figure of 8) device portrayed to protect someone, from falling, rather a gri-gri,
Even with a figure of eight (wearing gloves), belayer would be holding controlling hand, in downward position such that there was only rope stretch, to 'fall'/take-up once the guy fell on the rope.
Editing too made it look more dramatic.