Talk:Epic Rap Battles of History 59/@comment-26363928-20160227233038/@comment-5356835-20160228005459

I believe it's used whenever the camera is moving i.e. Spielberg's dolly shot and servel shots in deadpool vs boba fett. Since they are using a green screen, they need a fixed point on the green screen so the background knows where or how to move around when the camera is moving.