You don't have to rethink it. Phil and I already did that for you. You can do your CCTV thing and have it recognizable as a CCTV thing, even without noise effects. What makes video footage CCTV footage? The grayscales? The particular overlay things like "CAM1 (KITCHEN)"? Just because it has little to no scanlines and no noise at all doesn't mean it can't be instantly recognized as anything but CCTV footage if you have the grayscales and labels.
Practical example: Duke Nukem 3D has security cameras and monitors. If you activate a monitor, you're shown the scene as seen from the cameras linked to that monitor. There's no special effects involved -- no scanlines, no grain, not even a grayscale filter -- but the very fact that there are white corner brackets and a blinking ●REC makes it scream "these are CCTV images". The only real special effect here is that if you step back again, the monitor texture still shows the camera footage.