OK Stygg here is my take on what I am seeing in this animation. While the closer balls are going up and down, there shadows are moving from side to side. Wouldn't their location stay stationary as the balls go up and down? If the more distant ball is also moving like the closer ones then same thing as closer balls shadows only it's relative size and shadow transparency would be different. Roght now the shadows seem grouped and are moving in a similar fashion, but I could be wrong about that. OK the more distant ball is moving different. It appears to bounce streight up but on the way down it veers to the left.