[makomk]

From what I recall, modern graphics hardware has little or no support for video overlays. The fastest and easiest way to display video on modern systems is actually to feed it through the standard 3d-accelerated compositing stack, which means that it shows up in screenshots just like everything else. Some content providers don't like this because it provides a way to capture the video, so they insist on graphics hardware manufacturers providing some method of displaying video that blocks screen capture; if any modern graphics cards do support overlays it's almost entirely for DRM purposes rather than acceleration.

[TazeTSchnitzel]

I'm not so sure of that. Try playing a video on Windows XP with a cloned display. In some cases, the video will play on one screen, but not the other.