Check this out. I emailed both Cables America and Digitally Unique to ask if I could use the 50' Cables to Go RCA video cable as a sub cable. Here are the responses:

Cables America tech guy (who responded from a Cables to Go email address): "Yes, this cable should work fine in place of a subwoofer cable. It uses the same 75 ohm coaxial wire that a subwoofer cable uses."

Price for the 50' video cable at Cables America is $22.95 plus $8 shipping.

Digitally Unique tech guy: "Technically speaking, yes, you can use the 50' video cable. However, if you are true audiophile, you will want to keep looking for a sub-woofer interconnect cable. It has to do with impedance and noise. You might try Monster Cable. I think they max out at about 24 feet but they may build on for you."

Price at Digitally Unique is $19.95 plus $6 shipping.

What is interesting is John's observation that the description at Digitally Unique appears to be incorrect as it does not mention 75-ohm. The cables appear to be the same, however.

Any comments on the Digitally Unique response?