This video describes the "green screen" process in iMovie. The shirtless presenter has setup a green screen in his home along with several lights to provide realistic lighting. The presenter then places the object, in this case a porcelain troll, in front of the green screen. The background scene in this instance is a busy downtown area. By watching the background video while filming the green screen footage, the presenter is able to position the troll so it appears to be interacting with the background. The result is fun video of troll moving rapidly through a busy city.