That is a composite input port that comes with the driver board. You don't really need it for a portable unless you want to have video out to an external source. VGA requires 5 signal lines (RGBHV) and your driver board will require power and GND, which makes 7 wires. For composite, you only need 3 (the signal itself, power and GND). There should be connectors soldered onto your PCB that usually accept a male connector, however, for portables, usually these are either removed or we solder the video signals from the Wii directly onto the connector pins. The connections for each respective pin should be on the bottom silkscreen of your driver board PCB.