What principle is this film based on?

Movies are based on the principle of visual persistence.

A modern technology that uses photography (and recording) to record the images (and sounds) of external things on film, and projects the moving images onto the screen (and synchronizes the sounds) through projection (at the same time) to express certain contents.

Related information:

Film is a continuous image picture developed by the combination of mobile photography and slide show. It is a visual and auditory modern art, and it is also a synthesis of modern technology and art that can accommodate drama, photography, painting, music, dance, writing, sculpture, architecture and other arts.

According to the principle of visual persistence, the modern technology records the images (and sounds) of external things on the film by photography (and recording), and projects the moving images on the screen (and synchronizes the sounds) by projection (sound reproduction at the same time) to express certain contents.