Hmmm. It looks to me like the following happens.
The ball hits the flipper and begins to bounce off. Before it can do so, the flipper is released, which enables it to carry away the transferred energy/momentum from the ball. Before the ball can roll down any further, the flipper is engaged again comes back into contact with the ball while the flipper is at the top of its travel range, whatever mechanism holds it in place is where the flipper's energy and momentum go to instead of the ball.