I noticed in another thread you are trying to install InputRT (although having installation difficulties). It's an old program I wrote years ago that was very cool and powerful at the time. It would handle this although a solution integrated within DirectRT would be so much easier. Sadly, there isn't one--at least not in v2008 or earlier. We have a beta available now for v2010 and I believe it may have a function to take continuous keyboard input during a single stimulus (such as your video clip). I'll check into this and see. What version of DirectRT are you running now?

for other users: more on InputRT:
http://www.empirisoft.com/support/showthread.php?t=330