I've seen this video. Unless it's been edited, it looks like an unprovoked assault (by the cop) with a deadly weapon. If this is the case, the crook needs some serious jail time. Unfortunately, I'll bet that the prosecutor will come up with some ch!ck&nsh!t excuse not to press charges.
The prosecutor should know better, since the FBI is involved. If the locals don't do it, the Feds *will*.