The one I pointed out doesn't have a users manual for download so I don't have exact details on it. I believe the cameras from the same manufacturer use BNC connector so adapters would be needed. There are probably other video processors used by others. I hope maybe some one will have more information for you.
Basically you can run the four video signals into the processor and it can cycle though them in sequence or I believe put all four on to one screen divided by four. The output goes to the TV. The audio is not supported and in some areas maybe illegal for sound anyway.
Does the TV have a video input where you have tried one of the cameras now?
Do you want all cameras on and then processed? As they could be turned on and off by the software. Though I believe you had no luck with the software.
I will try and find more details
This site is a generic Automation Site. You may find added information on video processing there also.
http://www.cocoontech.com/forums/