First, you need to have purchased the Movie Studio level from the PSN store or the Pain store. Use the same launcher you used to get Helmet PI. Along the edge of the Gladiator movie set, there is a camera on a long track. Launch at it and grab the camera. You should start spinning around the camera while it starts moving down the track. Ooch it down the track until it hits the explosive crates at the end of the track. Make sure the camera hits the crates and not you, and make sure the crates explode. Do this 50 times.