If it weren't, we wouldn't have all those wonderful TV shows about "world's dumbest criminals" and "wildest car chases 7". The footage is usually taken from either dashboard- or shoulder-mounted video cameras. If the police have cameras of everything they do while on the job, it's tremendous protection for them against accusations of abuse of power, etc. How easy would it have been for the police to shut down the pepper-spray criticism you mentioned if they can show the entire footage instead of a narrowly edited clib devoid of context?

Regardless, I have to agree with moondog that law enforcement can't have it both ways: "public acces precludes any expectation of privacy" means, at the same time as allowing warrantless GPS tracking, that videotaping the police as public workers in a public venue and acting in an official capacity is (or should be) constitionally protected. After all, the constitution was created specifically to protect citizens from the abuse of government.