Ok, so obviously you have to talk to him about it. You asked how to bring it up again. Just tell him you need to talk to him because something's been bothering you, sit him down and launch right in. Just explain that he really needs to talk to you about anything like that before he does it. Maybe you'll agree, maybe not but he has to talk to you first. It could be the case that he thought that he could surprise you with it and you wouldn't feel violated, sometimes guys are just stupid.
However if you have any concern that that wasn't the case then you're going to have to take more serious action. You're not going to be able to enjoy sex with this dude if you're constantly checking that you're not being recorded.
Before I did anything else with him I would be doing a quick search of the internet because there is the possibility that he's done this before and you haven't noticed the camera, then I would demand that he puts the camera away, or only do it in your bedroom, not his.
Don't have sex with him again until you're sure you can trust him.