I just got an official Nintendo s-video cable. For some reason, the red and white cables are reversed. On every other cable I own, along with the inputs on the TV, the order of connections is yellow/white/red. This cable is s-video/red/white. I guess I need to find a game that has distinct left/right sounds so I can test that the cables are wired correctly.
*edit*
I tested the sound and it is wired correctly. I got this cable from Japan, but I can't imagine that Japanese audio inputs are reversed. I guess the s-video cable is just like that.