The movie you recorded by fraps is too big, especially while the output is avi file format. cause while recording, there isn't enough time to encode the movie. The movie frames are slightly compressed, but still require a large amount of disk space due to the high resolutions.
First select the target framerate for the movie, which indicates how many frames will be included in the movie each second. You can currently choose from 25, 30, 50 or 60 fps.
In the game press the Video Capture Hotkey (F9) when you want to start recording. While recording the frame rate counter will turn red. When you want to end your movie, press the button again to stop recording. You will now find the movie saved in your default folder.