Due to forum rules we are unable to advise for specific ways to do this for backup purposes. However, if you check the bottom of the first post here you will see links to where you can find such information with reviews & sometimes instructions: CODECs list for Movies/Audio/ Alternate players / Video help forums/ video-mp3 fixers

BTW Nero can make copies of DVD's on condition they don't hold protection from such, such as macrovision, CSS encryption, etc. You either make a disk image or extract the video vbs files is the way it's usually done. After that the choice is yours, to burn those files to another disk, else convert them into a format such as divx or mpeg 4 or H.264, Mpeg 2, etc.