Winxp running wmp in IE
Neither Printscreen nor Gadwin are capable of capturing the image
I can only assume that is is something to do with how the memory is captured/stored for video vs normal apps
Apparently turning off video acceleration works, and its supposedly because printscreen takes a snapshot of the screen buffer before rendering is done where needed on the graphics card. If its a codec thats GPU accelerated, doing that will make the performance significantly worse.
Alternately you can use VLC and use that to take a snapshot - It dosen't require any fancy stuff, and will yield VERY good screenshots - you can use the shortcut - ctrl alt s there.
When a program is using an "Overlay" to play a video, what your seeing there does not actually exist on the desktop "software". A hole is left at that location, and the video card itself , is rendering the video into that hole directly via hardware, to be displayed only on the monitor.
Most of the video programs can be switched out of Overlay mode, including WMP in XP. It is found in the display or video area in the more advanced options of WMP. Once you switch off overlay, a little bit more cpu is used, instead of rendering it at the GPU. The picture will then actually exist "on the desktop", and a screen grab or even video stream snag can occur.
It is easier to adjust it in many of the 3rd party video programs, than it is to adjust it in DXdiag (directX diagnostics progam XP only) Or via the system itself. MCP and VLC have changing the render type faster to get to. In windows media player it is not as quick to get to but it is there.