The file claw_pix_example01_movie.mp4 is an MPEG-4 animation created by QuickTime Pro out of PNG files which were created by the MATLAB script CLAW_PIX from solution data generated by CLAWPACK.
In this animation, the 1D advection equation
Qt + U * Qx = 0
is being solved at successive time steps. There are 50
spatial cells involved, and 10 time steps are taken.
The boundary conditions at both ends are 0-order extrapolation,
that is, the data at the end points is simply copied to the
ghost cells that are appended on the left and right.