He jumped too late, and so his toes caught, while still rising. It then spun him into the ground. Moving ropes can screw up your instincts to jump them, unless you pay proper attention (and over jump).
Notice that he didn't make any effort to catch himself. This isn't a person that normally does things like this or the crash wouldn't have been a solid faceplant.
I did very similar as a pre teen at a weekend school thing where I was running and tried to jump over a bench that was attached to a pole, I'd don't it several times, I miscalculated and slammed my shen into the front of it and ate shit.
It was right in front of an older guy I respected too, I felt so embarrassed and my knee hurt for fucking days.
Don't remember how bad my knee was exactly, but remember the shame