Helo Chris,
A product having a CE mark does not necesarily make it legal to use it for a particular application.
For most electrical products The CE mark in general only indicates that the manufacture belives the product meets the relevant standards as they can self certify. Some product categories are different - such as gas appliances - where the product has to be surveyed and tested and approved by a notified body before it can have the CE mark awarded. Abd with gas products they must have a CE mark before they can be sold in the EU.
Without seeing the camera system, I cannot be sure but I suspect that the CE mark only referes to the manufacturing of the product, rather than its possible uses.
Just as an analogy, you can buy a car which is of an approved design, but that approval does not mean you are allowed to excede the speed limit.