I always use print screen, but this is not liked on some servers as it makes your plane "pause" in mid air whilst your machine writes the screen to buffer.
Make a recording of your track. Then replay it until you get to the moment you wish to capture. Hit pause. Go to externals - your plane, friendly, enemy - whatever - and pan around, zoom in and out till you have the ideal picture framed. Hit printcreen.
The screenshot it then saved in your Forgotten Battles Folder. You can then open it up with photoshop or whatever to resize, crop, touch up - and generally make it look cool 8)
Well, I am back up and running now, at least for the internet and email! Next comes the games. Its reinstalling the tv card drivers that I am dreading. Once I am up and running I may post some little screenies to show you my comical flying style!