CCTV or any cameras, etc.. while in some ways may act as a deterrent just from them seeing it.. not always though. its more of a reactionary thing. At least if something happens, the cameras may capture what the person looks like, to be able to be passed onto police.
Beyond good basic locks.. a secondary device is always a good option.
Problem with them is.. most of them are actually so poorly designed for what they need to do.
Most of any of your chair, bar, etc locks.. are that its usually not the lock/bar/chain itself that fails.. its that the way they are screwed in. They are screwed in the same direction of the FORCE if someone was trying to say kick the door down. they are kicking towards the door, the same direction the screws are facing. they are going to be the failing point and could often be just ripped out with enough force.
We own one of these, and thing its a much better option.
It actually screws in on the inside of the frame, the screws going horizontal to the direction of force, making it harder for the screws to rip out (If anything would more likely break the frame, if there is enough force).