Check out this article, which includes a video of Connecticut state troopers discussing how to lie in an arrest report. The police did not realize that the camera they confiscated was still recording their conversation.
This video is from 2015. In 2016, the ACLU filed a lawsuit, which is still pending. A state police internal affairs investigation cleared the officers of any misconduct even though the officers were recorded discussing what they could say to justify their actions and added that they “gotta cover our ass.”
Video is useful to expose police misconduct, but when the police investigate themselves, civilian complaints are not taken seriously and brutality often goes unchecked.