The body cameras are for uniformed officers primarily. (Undercover detectives certainly aren't going to use them.) So the recordings are of (at least theoritically) public interactions. Law Enforcement is still working out exactly how to handle the video. A big issue is simply storing and indexing the huge amount of data. So far the various departments that use them seem to be gravitating towards only pulling and reviewing video for investigations into Officer Complaints (i.e. some complaint about an incident or officer by a citizen, AKA "Internal Affairs") and for evidence for criminal proceedings. Departments usually end up more concerned with protecting the public's privacy than with protecting any secrets of their own.
One interesting statistic from departments that are already using body cams. The number of complaints against officers by the public drops by a large percentage once the public realizes that the videos cut both ways AND officers realize how some of their behaviour looks to the public.