Say you've got a movie at NxN resolution, in RGB format.
Say the movie is meant to run at 10 frames per second.
Say the RGB value at each pixel in a frame of the movie is actually an encoded direction vector.
Say that each pixel in the movie maps to one vertex in the grid.
Say you take the direction vector encoded in each pixel of the movie to be a velocity.
Say you play back the movie, moving the vertices in the grid along their direction vectors (10 frames per second).
It should look pretty cool.