I'm not unreasonably worried about my coworkers, compared to a software-controlled camera they'd be wearing on their heads and pointing at our code, internal docs, customer information, etc.

And yes, if someone made a habit of pointing their cellphone camera at the screen all day, I would ask them to please knock it off.

I don't trust Facebook installing cameras in our workspace, or trust that they couldn't be compromised by another party who might want to watch what we're doing.