Again, exceptions don't prove the rule.
You have an odd definition of "exceptions", when I specifically included both the bad cops and the rest of their departments. "But you left out that one really really good cop in a coma for the past 30 years!"
And bystander videos do not exactly tell the whole story.
True enough. Why, in that first video I linked, you don't get to see the context - That the guy had just run over a spike mat, lost control of the vehicle, and almost hit a cop. Clearly that missing details justifies half a dozen armed thugs beating the shit out of an unconscious guy lying bleeding on the side of the highway. Damned biased bystanders, always trying to make the police look bad!
We get to see a far more complete portrayal of events.
Except, of course, when the cameras "malfunction" at those very convenient moments when the accused suddenly has an attack of clumsiness and walks into a brick wall... Repeatedly.
That is why police body cams are so much more useful.
And that is why police hate hate hate mandatory camera policies to the point that they piss and moan and vandalized the cameras and threaten to go on illegal strikes over them.