Safari Books Online is a digital library providing on-demand subscription access to thousands of learning resources.
Within a movie strip there is some usable footage, and when dealing with footage there are some important considerations. When you film, the director calls for quiet on the set, and the cameraman starts filming. There may be a clapper snapped in camera view to document the scene and to provide a nice sync point for audio to the film. The director then calls for "action" and the actors start acting. The action ends, and the director yells "cut" and the camera rolls to a stop.
NOTE
The word "footage" comes from the fact that a reel of real film stock was once sold in feet. At 24 FPS, you shot 2 feet of film per second.