The MiniX uses a quite different AV cable which I managed to track down to a seller based in The Netherlands. It is called a TRRS in other words a tip ring ring sleeve cable.
As you can see in this blog the length of the plug should be longer than normal plugs otherwise it will not work. It should be 14 + 2,5 or preferably 17 millimeters. I hope it will work with this one as pinouts can be very different on various versions.
Pinout should be:
Pin 1 (tip): video
Pin 2: Audio L
Pin 3: Audio R
Pin 4: Ground
Price is 8,95 euro’s .
Learn more about the TRSS sleeve cables here