cctv advice and recommendations

All I recently moved into a new house with 4 CCTV cameras and a digital recorder system (picture attached) The old seller told me that his cameras fed straight from the DVR into the bedroom and that all I had to do was insert the aerial into my TV and the camera would appear as a TV channel...

Hi Guys, I'm planning on installing a CCTV system. I'm doing it myself so I figure POE will make life easier. I was planning on buying a complete NVR system but now I am thinking of sourcing the camera's and NVR separately because of specific needs, but I am confused about compatibility and...