Each time the rotor is able to go up again until the maximum height from where it left. As the friction between the rotor hinge and the plastic slide is not negligible, exactly as the air friction, it could seem to be in front of a perpetual motion of a physical system able to generate energy from nothing...
Actually a trick exists: each of three expansions of the moving object has a little magnet. In proper time it is attracted and repelled by an electromagnet that is in the slide support; this electromagnet is controlled by a transistor and a little battery. In fact, the rotor accelerate considerably when it passes in this area.