The file tcell_flow_movie.mp4 is an MPEG-4 animation created by the MATLAB script TCELL_FLOW_MOVIE.
In this animation, the normalized velocity vectors are shown. If the velocities are shown to scale, the most interesting behavior (in the recessed area below the main flow) will be too small to see! In this flow, the inflow parameter is a relatively high value of 5/3 for timesteps 1 to 250, dropping to 1/3 for timesteps 251 to 500. While the main flow does nothing interesting, in the recessed area the center of the vortex will move as the parameter changes, and you can just see even smaller vortices starting in the corners. There are notable transient periods just after timesteps 1 and 251 as the flow adjusts.