As the guy collides with the ball, he pushes off with his feet. He applies a torque to the ball, thus speeding up its rotation rate. Not to be outdone, the ball applies a torque back on the guy, causing him to spin in the opposite direction. The result of all of this: the ball speeds up, the guy slows down, and he starts spinning in the opposite direction to the ball. Linear and angular momentum are conserved, he sticks the landing, and everyone is happy! Now that's impressive.