Long story short, you play the film with fraps in the background. Use fraps to capture the footage while playing the film. Edit said footage into a video when you are done.
That's the short version.
The long version includes bits about figuring out what you want to do, planning all the shots, any music (it seems common in AH films) and then working to get those shots with fraps and the film viewer. If you've got it all planned out it's easier to assemble into a video when you're done.
