Nejspíš to nefunguje vůbec. Normální převodník VGA na S video stojí mnohem víc a je to krabička.
EDIT: tak to cos koupil stojí na e-bay 32Kč a výslovně tam píšou:

It will work with laptops and desktops with VGA cards that has TV-Out function capability through the VGA connector.
Note:
Please be sure to the Video Card of your system supports TV (RCA/S-Video) output through VGA port. Not every video card will work with this adaptor. Only certain video cards which have TV Output function built into VGA port will work through this adaptor.