print screen definitely works in windowed mode, but doesn't seem to work properly in fullscreen (3d) mode.
A while back I wrote a simple movieplayer that plays an AVI-file.
This movieplayer cannot skip forwards or backwards or something else, but was designed to take screenshots from movies, because playing a movie in Media Player and pressing "Prt Scr" doesn't capture the movie (just the media player window, the portion where the movie is playing, is black).
I used "Graphics3D", because "Dithering" doesn't work when using "Graphics" (2D).
All screenshots taken with this movieplayer are perfect (I've taken about 150 screenshots from DIVX-movies).
Here are a few of them:
http://users.pandora.be/vge/Blitz3D
Of course the picture quality is now a little reduced, because:
1. the movie is scaled from original size (Hot Chick: 896x504, Johnny English: 512x288) to full screen (1024x768)
2. the screenshots are converted to JPG
3. the movie is ripped from DVD and compressed to DIVX
The file "Johnny English 1.jpg" was taken in a fast moving part of the movie.
And for the ones who want to use my movieplayer, the source code is also uploaded to my website (see link above).
You can load a movie by right-clicking a movie in Windows and selecting "Open with" and then browse to the compiled exe (you have to do this yourself, downloading the source code and compiling is faster than downloading the EXE for modem-users).
See comments in the source code for options (pressing F8 will take screenshot, ...)
Screenshots are saved to "C:\MoviePlayer\Screenshots", but you can alter this if you want (global var: ScreenshotDir$).