The following video is NOT for the feint of heart. Not. If your hear is feint, go away. Now. I am not kidding. You have been warned.
Obviously, the rocking chair is going to move. But notice that the clothing (at least I think it is clothing, not a person) on the bed to the right is moving a little the whole time. Also, the rocking chair is moving, I think, almost imperceptibly. Is there a string attached to it?