I'm working in 10.04 Lucid. All my video players (Movie Player and VLC) and the preview windows in editors (OpenShot and Pitivi) will only display a black screen when playing a video. The sound is fine and the videos work fine on other computers.
I have tried multiple formats from varying sources .MOV taken from old ffmpeg projects, .AVI straight from a camera, .MP4 using h.264 from OpenShot on another system, .OGV from a gtk-recordmydesktop session on this very computer. I even get a pure black screen in the viewer when starting a remote session in VNC.
This box has a GeForce 8400 GS using the proprietary Nvidia drivers in case it may be a card problem or setting.
I'm at a loss. The best suggestions I have is try re-installing the drivers or trying the non-proprietary nv driver. If the problem is still there with the nv driver, then it is most likely not a driver issue.
Good Luck
I found this worked.
Open the Configuration Editor by running
in the terminal.
Navigate to system → gstreamer → 0.10 → default
Double-click on videosink and change the setting from autovideosink to ximagesink