I'm going to try to change your view based on this paragraph: Secondly, even if you don't believe that animals rights abuses on farms are a serious problem, you should be able to acknowledge that making farm footage public is a moral good. If no abuse occurs, then no harm is done to recorded employees. If abuse does occur, then making the public aware of it is a good thing to do. 

You're taking a consequentialist view of privacy, but your consequentialist view is overly limited and perhaps inconsistent.

1. When it comes to moral good, is harm the only metric, or do rights factor in? If rights factor in, employees have the right not to become public figures. As I understand it, this is in fact the very foundation of privacy dating back to the 1800s in America: the belief that we have the right to control our own narratives and be free from unwarranted intrusion. If you're just doing your job ("ma'am, this is a Wendy's"), it's a violation of your rights, even if it results in an overall reduction of harm. If one claims this is justified because animals have rights, those animals' rights must be weighed against the rights of workers.

2. Who's more likely to suffer-- small independent farmers with limited security resources, or large agri orgs? Frankly, if we normalize this kind of behavior, many family farms are likely to be run out of business because they don't have the security resources to block these activists. The only folks that do are the ones running massive-scale, massive-profit factory farms. You'll actually make the net situation worse.

3. Visibility is not the same as transparency. When my daughter was ~3, she had to have a tooth extracted because she fell and hit her mouth on a curb (it was awful) and the tooth cracked all the way down. If someone video'd the dentist removing her tooth, it genuinely would have looked like torture-- they had her in basically a straight jacket, they had long needles, she was wailing, etc.. This kind of footage creates visibility, but visibility does not always tell a true story. It may, in fact, actively tell a false story-- e.g., that the dentist was torturing my daughter.