Everything is clear - he tricked her into sex, but who really filmed it? He obviously filmed it with a different camera than the one he had in his hands! A hidden camera does not give this angle and quality of shooting! So the cameraman in the room with a professional camera and a camera in his hands just a farce.
Now the girls have gotten their hands on some hot dick - now they can't share it! They don't even ask their stepbrother which one he likes better. They're using him like an orphan dick!