I had read about this the other evening and was really disturbed. My first reaction was the tired and cliched "if you're not guilty, then you have nothing to worry about."
The thing to me though, is that after they started putting cameras in police cars it was trumpeted as being such a great thing for the officers. How the cameras have saved so many officers and/or brought criminals to justice, that otherwise may have gotten away with their crimes. Think about all of those shows with police car footage, where someone gets pulled over, shoots a cop, and drives off. The storyline is something like "if it hadn't been for dashboard cameras, this officer's killers may have never been brought to justice."
But things work both ways. There have been some grievous abuses of citizens by the police, that may have never come to light if someone hadn't been there with a camera.
There are good cops and bad cops. I've had encounters with both types. Fortunately for me I've never had my skull cracked open by either. But I feel like, if we don't have the option to record our encounters with law enforcement on the same level that law enforcement has to record their encounters with us, then we are all in trouble. From the police standpoint, I can see the argument that a citizen's recording could be biased or doctored as it doesn't have the same type of safeguards that police footage is supposed to have. But again, this works both ways. I don't know if there is citizen oversight or some type of neutral chain of custody for police dashboard video, but I've heard more than a few accounts (first hand and news stories) of video becoming "lost." To me it's not right that the people in authority are the only ones with a copy of the tape. Citizen or cop, there can be bias and misuse either way, but this can be compensated for by combining videos from both as well as eye-witness accounts to reconcile the stories to gain a more accurate description of events.
In addition to having a camera available mounted in their car, the police also have the option of calling for backup to assist on the scene. As a citizen (I've been arrested before) I've never had the option of calling for backup/witnesses to my arrest. In a one on one encounter with a police officer, who is there to guarantee my safety and tell my side of the story? As far as I've ever experienced when it comes time to go to court, you already have a strike against your credibility because, to have an encounter with the police means that you had to have been doing something to get their attention. What hasn't really been brought up is why you've gotten their attention. Did you actually do something to warrant their attention or did the officer have you pegged for some other reason. The way you look, the car you drive, the people you know, the places you go, etc.
As someone already pointed out, a lot of authority amounts to trust. Who do we trust to safeguard our liberties and protect society in general. As people we mainly have to trust each other. I could create a nightmare for some random stranger right now by calling the police and making some false accusation. There are laws against this, but in the time it would take to sort this out, damage would be done. In the same way, a rouge police officer could do the same. I could have an encounter with the police right now and levy some accusation against an officer. Again, in the time it would take to sort this out, damage would be done.
I think that the police and citizenry are both well served with the right to record our interactions with each other. It could only stand to increase the amount of trust we have to place in each other and be an effective deterrent to any possible abuse of that trust by rouge authority. The best possible thing to happen right now for the police (nationally) would be for their union to stand up, support and encourage the rights of the people to record the police in the course of their jobs just as the people have encouraged the police to do the same.
Redundant facts in the course of figuring out a crime certainly could only help to serve justice and any differences between the facts (recordings) would strengthen a case one way or another. Why should the police be the only arbiter of the facts and evidence?