(Updated slightly for clarity.)
Here's what apparently happened: Someone in Pontiac Michigan called 911 to report being nervous about a man seen walking with his hands in his pockets, to which the obvious reaction is "Wait, what?" The real cause for the nervousness and the call, one suspects, is that the man in question is black.
This puts the police in a difficult situation. If they ignore the call, there's a chance that the caller actually had some legitimate reason to feel nervous but was for whatever reason unable to articulate it. On the other hand, if they do anything there's a good chance they'll end up at least inconveniencing and annoying someone who's doing nothing wrong. On the whole, I think there's a lot to be said for checking out the call but not giving it an especially high priority, and being friendly about it. For the most part, that's what the cops did here.
If I'd been in the shoes of the guy who shot and posted the video I'd probably have been pissed as well. Despite the video's misleading title ("Police State"), in the video itself he mainly appears to blame the 911 caller. But he's also understandably upset about being confronted by the police. More on that in a minute, but first the video:
The officer doesn't handle it perfectly (he tells the guy he's making people nervous, which is a tad ridiculous), but for the most part he seems reasonable and not hostile. He even does a high-five to try to be friendly (you may think it's silly, but at least he's trying), and his reaction to being recorded is to take out his own cell phone and shoot a reverse angle. (As a fan of filmmaking, it strikes me that it's a pity we don't have both videos -- the cop's and the civilian's -- so we could edit them together.)
This officer's non-hostile reaction to be recorded on video stands in contrast to that of other cops who have gone so far as to illegally arrest people for shooting video of them. Darren Wilson, who shot Michael Brown in Ferguson Missouri, did that on an earlier occasion, for example. Some jurisdictions have even tried to prosecute people for violation of laws against eavesdropping and wiretapping that were never intended to prohibit shooting video in a public place or on one's own property.
Now on why it's reasonable to worry when confronted by the police: Watch this rap video below from Rob Hustle. You don't have to listen to it -- the words are over the top and even bigoted against police -- but the videos are as far as I know on the level and disturbing. There are bad cops out there, and loyalty to fellow officers appears to keep too many good cops from getting the bad ones off the force.
It's worth keeping in mind, of course, that one could also assemble videos of police officer behaving with great courage, kindness, and compassion. And one could also compile clips of members of some particular ethnic or religions group behaving badly as well. It's ridiculous to ascribe the actions of some individuals in a group to the group as a whole. But it's still disturbing when some of those whose job it is to enforce the law and protect society from crime themselves engage in criminal violence.