I hooked up my Harman Kardon AVR-235 receiver last night. I have my DVD Player (Cyberhome DVR 1600), Cable box (Motorola 6412 from Comcast Cable) and my XBOX connected to it. I also have an S-Video cable going from Monitor connector at the back of the receiver to my TV set.
I can get audio working on all three inputs, but I cannot get any of them to show video.
I have the AVR335 and on my receiver you need to associate the video input with the sound input. For example, the video input for the satelite box is Video 2. However, the default audio input associated with Video 2 is Analog 2. I had to change that to Optical 2.