This is "Sir Treven" and he is jousting. As you can see Dad is the horse.
Here is the list of events, Trev stands on the couch and says, "Stand your ready." Then he runs down jumps on his dad with his lance, yells "charge", dad runs(gallops) into the couch, Trev pretends to fall off moaning, then gets down on one knee as dad, who is now the King, knights Trev. Quite a series of events and absolutly hillarious to watch!