QuickTime Capping problem

The GoF teaser trailer is up (apparently) and it is TEH LOVELY! So naturally, I want to have a few stills from there to make icons with. I read a tip on how you screencap from QT and thought "Okay, I'll try" But when I paused the trailer, moved to the frame I wanted and Ctrl-copied it, nothing appeared in PSP when I tried to paste it in there. So I decided to use the 'Save target as..' function. Nada there. The same window comes up (the one with a lone Harry standing with the back half-facing us, although in trailer-mode). Does anyone know how I can solve this problem?

TIA