We were able to find the splice in a junction box in the ceiling in the garage. The cat5 bringing the video back to the control room only has one available pair which is being used for video. We do not have the whole cat 5 available.

Do you think the doorbird 2-wire would work? It would be (rg59) to (coax to ethernet balun) to (doorbird balun) to 2 wires running back to the control room to (doorbird balun) to network switch.

It seems like a lot to go wrong!