It shouldn't be up the the discretion of the jury to acquit in cases like this. The "missing video" exclusion should take care of this automatically. Basically, if there SHOULD have been video tapes (from police cars or body cameras) of an incident, and the videos are missing for any reason, then the presumption in any police said/accused said situation should be with the accused. The accused could still be convicted with hard evidence not obtained during the missing-video incident, but ALL "evidence" and police testimony associated with the missing-video incident would be excluded, and the accused's version of events presumed to be true.
And of course, if a police officer has a history of videos "missing" - or of video cameras "malfunctioning" - in police misconduct disputes, then this should be cause for being fired.