Moments later, this guy bounced off the ball and cracked his skull open on the side of the pool.
For every action there is an equal and opposite reaction. If that ball is inflated very well, its inertia will keep it from just flying away to the other side of the pool, as will the guy's angle of approach. The three likely outcomes are 1) The ball spins out from under him, leaving him to belly flop or fall backwards only slightly, causing little harm. 2) He manages to grip onto the ball enough to just be spun underwater as the ball turns mostly in place. 3) He bounces backward off the ball and hits his head.
Judging by how far out of the water that ball is floating and the angle he's about to hit it, I would say 3 is very likely.
---
Do you want ants? Because that's how you get ants.
