I recently got into buying S-video cables for all my video game system to get the best visual quality out of them as possible, without modifying them. While (RGB) SCART cables give the best visual quality possible in systems before the Sega Dreamcast, American TVs never had the SCART input on them, the best they had was the S-video input, thus my collecting of S-video as oppose to the SCART cables.
The 1st S-Video cables I bought were for the N64. After a lot of research, general consensus said the hybrid cables with the S-Video plug and Composite plug would only have the composite signal go through both plugs, as oppose to the S-Video plug having the S-Video signal (Y/C) go through it. So I was a little worried about buying these hybrid cables for the Saturn. But it turns out the hybrid problem with the N64 doesn’t apply to the Saturn.
Now a note on DITHERING: Dithering is a technique to create transparencies & increase the amount of color and shading that can be done on a system. The effect is achieved by using lines or dots which are then blurred by the video encoders that the system uses. The video encoder converts the RGB signal generated by the console's graphics processor to the YUV color space which most televisions use, which can cause artifacts that lead to blurring of adjacent pixels, particularly when the video quality is downgraded to composite. This has often been used as a cheap way to coax more color from a system's graphics processor than is usually possible.
A LOT of Sega Genesis and Saturn games use the dithering technique. You can only see the effects using composite cables, the technique is lost when using the S-video cables. The transparency/shading will look like a checkerboard on S-video. See in the below picture of Die Hard Trilogy of the comparison of Composite vs. S-Video dithering.
With the Saturn you have to pick your poison: get shaper graphics with horrible looking checkerboarding effect, or get a blurry image with transparency and shading.
The hybrid cable is good so you can easily switch plugs on a game-by-game basis for games do or don’t use a lot the dithering technique. For example, the games I have that I’d use S-video for are Alien Trilogy & Street Fighter Alpha; games that use a lot of dithering that I own that I’d use Composite for are NiGHTS & Die Hard Trilogy.