Round 1

Two men in green aprons stand in a room with a row of chairs, pulling on opposite ends of a long green strap; one man pulls the strap taut, causing the other to lurch forward and fall backward onto the chairs, then the man who fell stands up and pulls the strap, causing the other man to fall backward and out of frame, after which the man who fell stands up and pulls the strap, causing the other man to fall backward and out of frame, and finally the man who fell stands up and pulls the strap, causing the other man to fall backward and out of frame.