The video was just posted by Andrew Sullivan under the above title. He has requested his readers to translate the background voice. Here it is:
The voice: "Hit him, hit him with the baton, hit him with the baton... Pull him, pull him... Thugs should go to prison, thugs should go to prison..."
There are voices toward the end that are not clear. Then the policeman pulls the young man from the ground, continue hitting him, ordering him "Don't move!" although he looked only half conscious.