Being taped doing anything without my permission is an invasion of privacy and surely breaches some sort of privacy law. When I read your question, I felt my heart start to race, I began to feel unsafe. I can't really explain why at the moment, I'm not the best this morning, but it almost feels like by letting someone else film me, they have the power, I become vulnerable and powerless.
This could all be because of how I am feeling at the moment, but I would still feel uncomfortable with it.
If something like this has happened to you, it is important to confront the person. In person is always best, but not always practical, so by phone or email. Get your knowledge up to date on the privacy laws, and have the 'facts' at hand and ready to produce.
I was watching a documentary on the 'community' based TV channel a few years ago, when suddenly I saw myself. I kept watching and staring in disbelief, and then I appeared again, later on. I had absolutely no idea. At that stage, my PTSD was not as 'pronounced' as it is now, and I was still able to hold it together, but I still called the TV broadcasting station, told them of my situation and they put me in touch with the people who had made the documentary. I told them it was illegal for them to have put me in there without permission. Now, I'm not talking about background faces, this was of me participating in something that had a strong meaning to me. I was flattered, I guess, that they chose this footage to put in, as it really did serve the purpose of the documentary, but was frustrated I wasn't told or asked permission, as I probably would have said no. It was a special, sacred time and place for me, and to be intruded upon like that was almost earth shattering.
They ended up cutting that section out apparently, and only using another small section of footage that I had approved. It was too late then anyway, it had already been aired...