A white ball spins on top of a jet of water. It is not tied to anything any more than aeroplanes are tied to the sky.
It is the principle of aerodynamics that keeps it in the air: the water on the upper side of the ball flows faster than that underneath it. You can take the ball in your hand any time you like and put it back onto the water jet. As long as water pressure, water diameter and angle of inclination, size and weight of the ball are just right, this phenomenon will occur.