Movies are about time. You can take that momentum and manipulate time as well, or you can deliberately slow it down, stop it, and start it again. There is no other art form that does that type of manipulation in that way.
When people in stadiums do the Wave, it's the group-mind collective organism spontaneously organizing itself to express an emotion, pass time, and reflect the joy of seeing the rhythms of many as one, a visual rhyming or music in which everyone senses where the motion is going.