The only thing I noticed is that the DVR model exact model is not listed. I did configure another similar model which allows me to change channels etc but video does not work.
That isn't relevant. The video should be present the moment you plug in the cable before you do any setting up.
Unfortunately I can't think why the Yellow Composite/S-Video cable should work on the TV and not on the Slingbox, assuming you have selected the correct input.