Indeed. Openly OR clandestinely. And any cop/department/other government entity who prevents it should be fined/fired/eliminated.
I'm coming around to the notion that all cops should have a minividcam that they are REQUIRED to wear and have running at all times, and that cannot be turned off (by them).
If cops, or more critically the police unions, were smart about it, they would want every minute they were on duty filmed for their own protection to provide credible evidence of their behavior. That they instead act like thugs smashing cell phone cameras speaks volumes about their behavior.