Suggest using AnyDVD in conjunction with CloneDVD, which is available at SlySoft (http://www.slysoft.com) to decrypt and remove copy protection from your Commercial DVD Movies. DVD Decrypter is getting rather outdated and is unable to decrypt and remove copy protection from newer Commercial DVD Movies. AnyDVD is routinely upgraded and improved to decrypt and remove copy protection from the newer Commercial DVD Movies.
Below is an AnyDVD-CloneDVD User Tutorial that details the use of these two programs ->
To help distinguish between the various Audio Streams contained on a DVD Movie suggest viewing the below Forum posting and note the comments in posting #6.