I have a dual monitor set-up on my inhouse PC. I have the same issue you have. I can only play videos (or other graphics intensive apps) on one monitor at a time. I think it's something to do with DirectX. I say this because I use UltraMon to let me have separate wallpapers and screensavers and I can only run 1 screensaver at a time that uses DirectX. For example, I have the SereneScreen (3D aquarium that uses DirectX) running on one monitor and starfield simulation (non-DirectX) on the other monitor. If I try to run the SereneScreen on both it won't let me. I think this is just a software limitation, not a hardware problem.