Situations like this are the only time I feel the saying "if you don't have anything to hide, you'd let people look" is appropriate, when concerning people with power "over" common folk. This wouldn't apply to officers doing plainclothes or undercover work, as there would be no reason for a bystander to assume they were a police officer being abusive or doing their job incompetently. This would apply to uniformed officers going outside of the bounds of what is reasonable. It's not a perfect solution, no, but it's a lot better than "uniformed officers have a right to privacy while uniformed and officering, and it is morally wrong to film them in the process of wrongdoing".
There must always be strong checks on authority, lest it be abused. Perhaps the US is up there in the list of offenders, but then again they're not the worst offender in the world by far. Any modern democratic nation is susceptible to authoritarians and fascists wresting control if they don't institute strong protections against it happening.
Everyone deserves the right to privacy and misconduct should be dealt with by the appropriate superiors/agencies and not by public shaming.
If, as in the common case, a police officer is performing their duty correctly, why should they as a private individual be singled out, maligned, their personal safety be threatened, etc. etc?
If you’re coming at this from e.g. the US perspective where the situation with police is a very stylized us/them, this may feel odd.