Don't integrate it into the gun, integrate it into the uniform. It shouldn't be active only when a weapons clears the holster, it should be active while the officer is on duty. It'd be a win-win. Excessive force lawsuits against cops will likely drop when you've got video evidence (no more "incidents" for the 'race-baiting poverty pimps' to exploit for gain) and assure they're acquitted of false charges, and the rights of suspects are protected by the video evidence as well if the cops themselves violate the law, since it'll all be on record.
Technofixes aren't a total panacea, but I figure that if the government wants to keep us under surveillance, we should demand the same of them. The physical equipment required for basic A/V wouldn't be too hard (it'd have to be ruggedized, lightweight, low power, and the communications link robust enough to handle the data transmission). The legal framework for handling the data would have to be worked on (how it's stored, under what circumstances it'd be accessible, etc.) That way it makes it a bit easier to keep everyone honest.