Also, if I'm reading this right, a man filmed another man being assaulted, and now HE'S suing the city? Only the family/close friends should be able to sue. He wasn't the one attacked. He wasn't wronged. There is no reason for some random asshole that would rather film than help to sue the city. At the most, sue the cop.
Police officers must try to enforce all laws; even when doing so can sometimes look like retaliation. If the man who shot the video of Eric Garner being choked by police is indeed guilty of drug crimes, then he has no right to sue New York City for his arrest. Therefore, the police are likely being unfairly blamed for his arrest.
Eric Garner's death, after he gasped that he "can't breathe" because of a police chokehold, sent shockwaves through the world. Now, the person who captured the video of Garner's death, plans to sue New York City over an unfair drug arrest. This person is completely within their rights because the police have encouraged society's problems through unfair arrests, rather than eliminating them.
The police very likely did retaliate against him because he filmed the video. Although the officers eventually got away with their crime, his videotaping of the event did cause them a great deal of trouble and some bad publicity. Based on their past actions, it is likely they would find some way to retaliate.
Recently, more and more people have been capturing images and video of mistreatment at the hands of police. Sure, the police are not all bad, but many do need to be blamed for improper treatment and also protecting their own when they are acting inappropriately. Who knows if the drug arrest is legitimate, but with recent police actions, it is possible it is simply retaliation.