The problem being that the keeper of the records and the random police officer know one another, and those records "unfortunately" get lost. Unless somebody's got a grudge against the random officer, of course. But you're still dependent on the guy with the power.
I'm not talking 1984-the-police-own-all-the-cameras. It becomes cheap enough that some random person walking down the street can point a cellphone at the event as it happens, or a store owner's security camera can catch it on film, etc. Unless you are trying to imply that every random person will just happen to be friendly with any random police officer that gives you trouble.
I've heard (though I can't substantiate) that in some locations it is illegal to record, film, or photograph a police officer performing his or her duties. So, if this is true, in your scenario evidence of officers misbehaving wouldn't help you because it was obtained illegally.
YouTube changes the balance of power though. Before the case goes to trial, the entire jury pool has seen the police officer do whatever it is they did.
