Ive been having this problem with a laptop that uses a GeForce Go 7600 with both the latest versions on Resolume 3 so i know it not the known "3d acceleration" issue.
Basically when attempting to output video on a local plasma screen there is no video output (not even still image, fullscreen or window) from resolume.
However, if I set the plasma screen as a primary screen and drag resolume in the secondary screen (now the laptop) it plays at the plasma screen but i get no preview in the laptop screen.
Any ideas?