Depends on the type of movies you are tring to make & the type of input the burner software is going to use. If you are just making a backup of your DVD movies, then just use dvd shrink to compress them.
if it dvd copying then MR mix has the answer all sewn up dvd shrink will also backup the dvd to hard drive and then copy to dvd using your burning software i find nero 6 the best for this and the latest dvd shrink automaticaly opens up nero ready for the burn process.
dvd shrink click open disk this will read the dvd in your drive.
it will analyze it and tell you if it will fit on a 4.7gig dvd with a green bar at the top. then backup to a folder of your chioce.
hope this helps