I have Comcast as well. What I did was I used a double splitter on the coax right out of the wall, one line goes into the Replay unit and the other into the cable box. Both lines then go to the TV. Depends how many inputs you have on the TV though. Might be a quick fix for you for now instead of having to watch two TV's, until you can crack the case on your RTV unit to modify the software. When I get some time I will look into dstoffa's advice, as that is the best solution.