@Links - I crossposted with Joeylittle and you, and I want to echo what she and others have said. I don't think he means any harm but to keep you and him safe. Just has he has done all along.
Most people really have no idea how important it is to put up a notice or seek informed consent before putting up surveillance videos.
Something must have happened with someone that had him spooked enough to feel that more security was needed for his safety and the safety of his clients. He's a therapist and not a security expert. Maybe it wasn't even him, but someone else in the office.
I ride public transit with tons of security cameras (up to 10) on the buses, and when something weird happened, those cameras helped the police catch a really awful person. They are not CCTV and they do record audio, and that audio picked up on verbal threats and helped protect those on the bus. I go through stores with them all the time. They are super common. It doesn't rattle me to find them in any of those settings, or even the workplace. Heck, I have my own "nanny cams" in my own home and on my doorstep. (They were put there when home health came and someone was aggressive.) It was there to keep me and everyone else safe.
But despite my comfort with cameras in all those settings, even with audio, I'd be really uncomfortable with a camera in the therapy room without being told beforehand. Even when the therapist means no harm, like in this case, I'd still want to know if it was on during my sessions and who has access to any accidental footage of my sessions. I'd want to know who can see my face as I describe the worst trauma in my life. If it's someone more than just my therapist, I'd totally object. I would require it to not only be turned off, but for my therapist to cover up the camera every session. This is perhaps an overreaction, but it would help me feel safe again.
And it's extremely unlikely anyone but your therapist would ever see the footage, and that it does just sit in a hard drive until it is erased.
I have had my privacy breeched by a terrible therapist in a way that was very harmful and humiliating -- it was one of many horrible things the therapist did. The info went to one person who was not bound by privacy laws in the US, and they made it super public. The therapist was held accountable for their breech, and some much more serious criminal acts. But once the info went where it went, there was nothing that could be done to reign it back in. It was perfectly legal for a non-privacy law covered person to keep passing on the info. I did everything possible under the law and it was still impossible to stop them. The fact that I was in therapy was passed on and twisted, and it was awful. I won't go into the details as my situation was as very abnormal. I will say it did screw me up for some time and I can validate that someone with a history of any issues that bump up against this would naturally be worried. It's got to be disheartening that he overlooked that fact.
It's been important for me to maintain the therapy room as place where I'm totally sure that even my presence in the therapy room is totally confidential, something only the therapist and I know about, and the occasional person who walks by the waiting room. That privacy helps me feel safe.
Your concerns and discomfort are very reasonable. This is a mistake, a serious one, but likely a very unintentional one.
He should be willing to hear you out and take measures to help you feel comfortable again. Protected. Safe. And that your sessions are totally private in the way that you need them to be, so that you can continue to do good work with him. Don't give up on him. Talk this through with him.