Cable box audio/video input connections

I have Cox digital cable with a Pioneer voyager converter box. In the back of the box there are yellow, red and white connections for audio/video input and output. I recently got a blu ray player and would like to run it through the cable box so that I can watch DVDs and netflix on more than just the one TV. I called Cox communication and the tech support woman told me that I would not be able to run A/V through the box (she did not seem to be quite with it). This leads to my question.

If you cannot run A/V signals through the cable box, why are there "input" connections on the back of said box??

It makes no sense to me why Pioneer would put connections on their equipment if they cannt be used. I would appreciate anyones knowlege of what these connections are for if they cannot be used as above, or if they can be used in this fashion, how do I go about making the correct hookups?

Thanks in advance!

Never thought to look for a manual I searched all over including the Pioneer web site and found no manual available anywhere (except to purchase for an exhorbitant amount). So I sent an inquiry directly to Pioneer. I will post whatever answer they send.

As for the quality, that is not a concern of mine. I bought new TVs just before HD became reasonably priced so I am connected with 480i anyway. I cannot see dumping a pertectly good television just for a better picture, (or lack thereof depencing on your persective).

Thanks for your suggestions and input.