To check whether the video controller provides the required functions and whether the X device driver implements XVideo for any of them, one can use the xvinfo program.
Video playback programs that run under the X Window system, such as MPlayer, MythTV or xine, typically have an option to enable XVideo output.
This involves all windows being rendered to separate output buffers in memory first, and later combined to form a complete graphical interface.
In the event that the window manager doesn't directly support compositing, it is more difficult to isolate where the video stream should be rendered, because by the time it can be accelerated the output has already been turned into a single image.
When the video stream is added to the output, the graphics card can simply scan the co-ordinates of the canvas.
If the window manager doesn't support compositing, post processed hardware overlays using chroma keying as described in the previous paragraph can make it impossible to produce a proper screenshots of Xvideo applications.
It can also make it impossible to view this kind of playback on a secondary display when only one overlay is allowed at the hardware level.