Quick question on the side .....you said it was a "Samsung HD wall tv..." if it is HD then you have to have more then coax input!! HD would at least have the componet video input (blue,green,red)and a A/v input (yellow,red,white).
The RF modulator is the problem. cause it will shut off the coax input to it the minute the VCR-DVD recorder comes on. so the setup you have listed would not record anything cause your cable doesn't run to the VCR_DVD thing. There is no input to it that you mention?
does the VCR_DVD have a coax input and/or output
you could hook the cable box into the VCR-DVD and then hook the VCR-DVD to the TV!!
I hope this makes since at all.