I see, my primary problem with what they say is that it could seem very repetetive after a while, moans, could be added after many multiple scenarios with different context, specific dialog however, could seem awkward if done twice. The new CCTV in progress doesn't require you to install / upgrade camera tho hehe, and also allows you to watch multiple screens at a time (Should have mentioned that) so sound coming from a screen could create a cacophony.
Only ideas that comes to mind is visual context, speech bubbles, subtitles, or "mumbles" (due to CCTV low quality microphone) that add a lil context without exposing the content of the conversation.