How, its actually not too difficult to tell that its a different person, or filmed more than once. The quality of the man flying is much different than that of the one who climbs out.
An easy way to tell that it is fake is that if he were to fly with that velocity and reach that maximum height, if he even did land in the pool, it would slide. If he landed in that pool with it that shallow, he would break or fracture multiple bones. Even if he somehow did not break any bones, he would not be able to simply climb out as he did. The water would not slow him that much