Absolutely i think they should. In the usa many localities are giving police body cameras (DC is one such city). Video isnt always conclusive but man it makes me feel better that i have a camera on my dahsboard.
My son was pulled over in a routine traffic stop a few weeks ago (rightly so, he was speeding). He called me and put me on speaker. Initially the officer was being a bit unprofessional dispite my son being over the top polite, knowing i was listening. . Once i spoke up (through Bluetooth fed to my sons car radio) and assured the officer my son would cooperate and mentioned my backround the encounter turned 180 degrees and ended positively. I doubt it would have ended negatively had i not been on speaker but it would have been less than positive.
Video can have the same effect. People are on their best behavior when they know they are on the record. Officers are under a lot of stress doing a very tough job and if a video camera helps them stay focused and make better decisions then i am 100% for it. If force is justified then it protected the officer and if not then the citizenry needs to be protected from that officer. Hard to see a downside.