Well, news intern Mike Gore seems to have found the video on YouTube. You can see the whole verbal altercation that escalates into the officer initiating violence at the 50 second mark:
Thank Christ for cell phones with video cameras... And while I praised cops earlier for reporting this, it looks less proactive now. The impetus for taking him off duty wasn't just conscientious policing (the officer right next to the offending cop seems unfazed). It looks more like the officers knew a crowd was there, recording, and this was going to be exposed quickly. It looks like reactive PR damage control.