Awesome job man. There is a slight problem. Screenshots can't be captured while in demo playback. Not even if you pause the demo to try and take a shot. This isn't right because you could take screenshots while watching a demo in D2.
Perhaps demo playback code has a seperate section where the screen capture was designated and you just need to add the changes into that?
I will look into this. Can't be much of a problem. I guess that the demo playback code simply doesn't react to Alt+F9, because if you can take screenies there in D2 classic, there must be code for intercepting a key and dumping the screen to a file.