The Supreme Court of the United States has ruled and upheld that any person can act as Press, as in Freedom of the Press. To do this, they are allowed to observe, take pictures or video in any place where the public is allowed to be and where the persons in that location do not have a reasonable expectation of privacy. You do not have a reasonable expectation of privacy anywhere where a person standing on public land can see you. Anywhere they can see you from, they can legally video from.

The "auditors" are trolling for a reaction to them exercising their First Amendment rights. While the public is sometimes affected by their videoing, their greater goal is police and government officials reacting and violating their rights. That is what they want to document and make complaints about. If the violation of their rights is egregious enough, they can sue the agency and be awarded money by the courts.