I don't have a real answer to your question, but if you're trying to <font face="Console" size="3">prt scr</font> during a stream in Media Player, try going into the options and turning the Video Acceleration all the way down.

Options -> Performance -> Video Acceleration.

Slide it all the way to the left (None). You may now see a frame when you Paste into an image editing application instead of the stream. Sometimes it works for me, and sometimes it doesn't. Still, it's worth a shot.