My Ukrainian friend claimed it's the case with the new police force. They are extremely careful about turning those cams on before approaching anyone, even when they're helping an old lady through the street. I can't read the language to get primary sources myself, googling for English texts gave me only stories on how the judiciary system (not replaced) there is practically at war with the police (effectively rebuilt from ground after the last revolution).

Sadly, I can't see any western country doing it yet. Damn, in my home country there was a case of assault against police officer. A video got public showing the officer walking up to the guy, throwing him on the ground and proceeding to kick him. I believe the judge still took the cop's word.