The medium used to film also includes video cassettes of varying sizes. So Film is the capturing, on film stock, of pictures in motion. To capture is simply not enough to functionally define film, the viewing is an important aspect of film. Motion is only percieved upon viewing. Viewing is possible through the projection of images onto a screen or through the use of a VCP and television.
Film rolls through the projector and the same film is shown on the television.
So now film is the capturing, on film stock, and viewing of pictures in motion. This includes both pictures of objects in reality and those created through drawing,artistic collage, or sculpture. Motion is not a neccessity to be a film. If a filmmaker captures and views a dead fish, there is no motion because the fish is not moving. So the subjects don't have to move to be film.