The file cavity_flow_movie.mp4 is an MPEG-4 animation created by the MATLAB script CAVITY_FLOW_MOVIE.
In this animation, the normalized velocity vectors are shown. If the velocities are shown to scale, most of them are too small to see! This particular flow is pretty dull. The only "excitement" occurs at timestep 251, when the magnitude of the tangential flow parameter drops from 5/3 to 1/3.
The original data for this animation is in the CAVITY FLOW dataset directory.