"If you were WATCHING a film of the objects motion....." In this case a rolling ball. The statement was about observation, and not the kind of looking that includes any instruments other than the human eye. If Time is symmetrical, why is the energy expended by the ball asymmetrical ? This is the "Heat lost equals Heat gained" of High School physics. If some how the floor could impart energy to the ball as it rolls, it would keep rolling and your instruments would not detect it and you would not know which direction the ball is moving relative to it's "Starting" position. Time is symmetrical, therefore you have just as much chance of being in the future as you do being where you think you have already been. The only thing that convinces us is that we do not move backward and forward in time, is memory. If we do move backward and forward in time, so does the memory of this passage and therefore, like the ball, you have no idea if you are coming or going. This is like Plato's Cave...a case of limited perception, from the anchor of memory. Since we don't remember repeating the past, we don't know if we have.