And are you sure your laptop's S-Video is an input, meaning it can take video in? Most every S-Video port I've seen on laptops are output only, for the purpose of displaying its screen on a TV or routing through an AV receiver for example.
Also technically, just the yellow line out of those three "RCA phono" type connectors is called composite, since it carries a composite video signal with color (red, green, blue components), luminance, and chrominance all combined. The other two, red and white, are simply an analog stereo audio signal.