DVDShrink was abandoned many years ago, before the onset of structural protection added to dvds to prevent copying. It simply won’t work as a decryption program with those types of dvds. DVDDecrypter is another old decryption program that was at one time the very best, but development was stopped (forcibly) by Macrovision. It is also ineffective against most added protections above and beyond the usual CSS encryption.
DVDDecrypter was just a decryption program. Shrink combined decryption and transcoding ( a type of compression) to fit movies onto a single layer dvd.
If you want a modern decryption program, and don’t mind paying for it, look into AnyDVD and DVDFab. They are the two best for this.
The only free options are DVDFab HD Decrypter and DVDFab Passkey. DVDFab HD Decrypter is the free decryption/ripping section within DVDFab. It will continue to work even after the trial for the main part of DVDFab expires. The only caveat is that its decryption abilities will lag behind the commercial product by 4 to 8 weeks.
DVDFab Passkey is a new program that works in a similar fashion to AnyDVD. It is just for decryption and it is only free while still in beta. It will eventually be a commercial product. I haven’t tried it, but if it works like AnyDVD, you should be able to run it in the background to break encryption and let DVDShrink run as usual. With Passkey going, the dvd should look like it is unencrypted to DVDShrink.