None of these cables are 75 ohms tip to tip. This is because the RCA phono plug was never designed to be a constant impedence RF or Video connector (it is a PHONO plug) and there is no standard that defines its impedence.

For the short runs of cable that are normaly run in home video systems, and the low frequencies of the signals involved, the impedence of the actual cable doesn't make too much difference. The only reason to match the impedences in the system are to minimize reflections. In 1 meter of cable the reflection time is less than 5 nanoseconds. I don't think that the eye can distinguish this. I guarantee you you can plumb up your video sustem with good quality 50 ohm coax and you won't see a bit of difference.

My advice to somonne looking for interconnect cables would be to stay away from the cheep Radio Shack stuff because they are built poorly from inferior cable and connectors. I would buy good quality cables like the middle or high end monster cables. Mainly because they are built well and the cable and connectors are of a high quality. I would also keep the runs short, don't use a 3 meter cable if you only need to go 1 meter with it.