The VideoLAN Forums

When you play a video and move it from the primary to secondary screen.
The video goes black.
To alleviate or fix this problem you have to put it in the middle so a part of the window is in both screens. And then put it into the next screen.

I am playing VLC in my primary monitor, with the video card set-up to show any video playing in the "media player" full screen in the second monitor. I only rarely have any problems, and the video shows up in both windows. When I remote admin using RealVNC, I do only see black in the player window, but that saves me bandwhidth, so I'm fine with it.