Killjoys...j/k. Obviously its a trick. What I noticed is the guy sitting on the bench, after being carried away from his legs. He's stretching his shirt down in front of him. It looks like he's hiding his legs that are tucked up under there. The chick must be doing something similar. Contortionist folks I guess.

Then they stick their real legs into phony ones and walk around.

That's my guess.