Does the screen accept 12vdc?
It probably does, but I would verify before attempting anything, to prevent the risk of damaging equipment.
The color of the wires isn't going to help at all.
I have an extra plug on my ATX cable, can i use this to power my VM80 screen? The plug has a yellow, red, and black wire. Do i use the red or yellow for the positive?
If the screen is designed to run from the cigarette lighter (+12V unregulated) you can connect it to the M2 provided that you have not maxed out the current usage already. Use a voltmeter to verify that the correct voltage and polarity is observed. The Yellow wire of the M2 molex should give +12 and both black wires are ground. You have to figure out the screen end yourself.
ive got my lilliput running off of my M2-atx psu just fine.