How does it work?
The ball moves to the inside of the tube! The water and the ball in the tube experience a centrifugal force towards the outside. If you were to sit in the tube, you’d feel a force outwards as though you were on a fast carousel. Imagine that this centrifugal force creates a kind of artificial gravity which pulls things not downwards but outwards. The water in the tube can then be thought of as being like the sea, which is also pulled by the “gravity” to the outside of the tube. The “sky” therefore becomes the inside of the tube, and the ball floats on the sea, facing the inside as well.
