Welcome to the forums. You’ve dug up an old thread that isn’t quite the same situation that you have. If you’d like me to put your post into a new thread for you I can.
You won’t be able to copy commercially made dvds with Nero. Not by itself, since Nero will not break encryption on dvds. What you need is software for decryption, compression and burning to a disk.
The two best decryption programs are AnyDVD and DVDFab. DVDFab is an all in one program, while AnyDVD just breaks encryption…but you can let AnyDVD work in the background and use other programs with it.
There is still a way to backup dvds with free tools. DVDFab HD Decrypter is the free section within DVDFab and will continue to work as a decryption program that can rip the dvd to the hard drive even after the trial for the main part of the program expires. You can find it here: http://www.dvdfab.com/free.htm
Once you have the dvd on the hard drive, you can open the files with DVDShrink and compress them to fit a blank dvd. DVDShrink is free to download and use…so just click on it in the previous sentence and it will take you to the download here at cdfreaks. You can also use Nero Recode for this process if you prefer.
Once you have it to the correct size, you can burn with Nero or ImgBurn (a very good free burning program).
While you have the free trial for DVDFab working, you should explore its capabilities. You might find that the convenience of having everything in one program suits you.