What do you mean by promotion and demotion?

They refer to the technical means in film photography, which can achieve specific shooting effects by changing the speed at which the camera drives the film (or sensor) to rotate.

Upgrading shooting refers to increasing the shooting speed of camera-driven film (or sensor), usually 24 frames per second. When the shooting speed is higher than the normal speed, the shot image will have a slow-motion effect when it is shown. This technique is usually used to emphasize certain actions or create special visual effects.

Degraded shooting is to slow down the camera-driven film (or sensor) shooting speed, usually less than 24 frames per second. When the shooting speed is lower than the normal speed, the shot image will have a quick action effect when it is shown. This technique is often used to express the sense of speed or the special effects of time passing.