The simulation shows an overhead view of a ball moving through the air. When a ball is not rotating, air flows around it equally on both sides. When the ball rotates, the picture is no longer symmetric. Air has some viscosity, which basically means it is a little sticky. This means some of the air gets dragged along with the rotating ball. In the simulation the clockwise rotation of the ball causes the air to deflect down (from our overhead perspective...that would be to our right if we were looking at the ball coming straight at us). By Newton's Third Law, if the ball applies a force to deflect the air then the air applies an equal-and-opposite force to the ball. From our overhead perspective the ball would deflect up - that would be to the left if we were looking at the ball coming at us.