If you get 20 fps with fraps then that tells me you have a really really bad video card. Im a video editor and what i can tell you now for your answer, the only other way would be
In game when you are watching the demo
-Open consol type "startmovie 'name' 30"
-After finished recording, type in stopmovie in consol
Every single frame will be taken as a screenshot and sent to your esf folder.
-Get the program called bmp2avi
while in the program, click on the down arrow or whereever it says open, select the esf folder, and it will put all the ss's in list that were in the folder.
im going to stop here to make it simple, render it to your codec desire.
If you need any more help, contact me here via PM, or irc.gamesurge @ #rage.productions