As you probably know, filming cops doesn't work because the worst things they are doing are legal and mandated.

And the illegal things they are doing, like extortion, drug running, child trafficking, etc are not things where you film them, and then they will stop.
No, they will burn the city down first. They will hunt you down.

So, filming cops, as you say, is just a way of making two sides angry.
And, if i was to do this, i would set up drone like cameras in various places. Don't be seen, don't attract attention, and anonymously publish any videos that show anything criminal.

But, back to the beginning comment, the worst things that police officers do is legal AND mandated. In that, they are police officers. Officers of the court. Not police that are there to protect society. They are there to fine anyone that they can catch for any of a million trifling reasons. In other words, terrorism.