In addition to what Thalanor suggested (which is quite good), I got excited over this concept and couldn't resist sharing some thoughts as well.
To reduce the taxing affects of the CCTV system(s) on servers with many client data streams, it would be wise to process the CCTV block strings on the client side alone and utilize the vector information already received from the server. The vector information from the server (representing hard points such as ships, planets, people, blocks in general, node changes, etc.) could be reprocessed and reduced to be less taxing in the same fashion mentioned by Thalanor to render the CCTV images.
Furthermore, implementing user definable CCTV settings such as: texture quality, refresh rate, shadows, image filters, etc. would accommodate for varying PC hardware; allowing the user to tailor the settings however well their system can handle it.
Another suggestion would be to add proximity to the CCTV blocks by implementing a radius to each CCTV block to only allow it to display an image while within proximity of say 30 meters for example.
Create two blocks: CCTV Display and CCTV Camera. These should be self explanatory in how they would link together. The video string would primarily activated and controlled by the Display block.
Enable the CCTV blocks to have an ON/OFF feature and allow them to link to logic blocks for seamless interaction. Fore example: a simple switch could turn on several CCTVs at once; placing activation blocks in or around an entrance could activate a CCTV block in a distant security room which could be linked to a CCTV Camera block facing the entrance that was trespassed; spotlight mode would only activate the CCTV when a certain type of object or person passed within line of site of the CCTV Camera block at say 0 to 1000 meters.
Perhaps a more complicated solution would be to add an occlusion layer directly behind the CCTV screen to prevent it from rendering as long as the face of the screen is not in line of site. Perhaps include most other blocks in this occlusion effect as well to eliminate a scenario in which too many CCTVs are located with 30 meters of each other but happen to be out of site (behind walls).
Allow CCTV blocks to perform larger (border-less) grid arrangements; the arrangements would be limited to rectangular or square X/Y grid patterns such as: 2x2, 3x4, 5x5, etc. The maximum grid size would have to have a limit of course as not to get carried away with.
Filters could include: Infrared, Wireframe, Colored nodes only with distance in meters and colors determined by faction color (for larger screen arrangements), X-Ray scanning of structures in the form of a very short recording clip with replay (recordings get wiped or store a limited number of recordings; recordings get erased after each new recording) or simply to take an X-Ray picture via the CCTV Camera block and report it back to the screen.
Most of my suggestions are contingent on the system being well optimized in much the way Thalanor and I have suggested; or perhaps many better solutions exist -I'm sure of. I didn't give myself the necessary time to revise this little article, so please excuse any errors or less than thought out suggestions.
Plenty of games offer this type of feature via car mirrors and community mods, it simply takes time to develop and work out bugs. In my opinion, this one would be well worth it considering how limited views are while inside ships and space stations.
I'm all for this idea and think it would provide a whole new experiences and approach to playing the game. Please support!