Decrypter will only rip the files to the hard drive. It will not compress them down to a size that will fit onto a dvdr disk.
Download DVDShrink and use it instead. The latest version, 3.1.2 will rip, compress and even burn with Nero. It is a free download, look here: www.dvdshrink.info
Lots of information on that site on how to use the program.
If you run into a dvd that Shrink can’t rip to the hard drive, or if you want to remove rce protection (not common), use DVDDecrypter in file mode to put it on the hard drive and then use Shrink (tell it to open files instead of a disk).
Decrypter has other uses though. If you are working with a dvd that you know doesn’t need compression—not often found in commercial dvds—you can read it in iso mode, putting it on the hard drive, then write in iso mode onto a new blank disk.