Let us assume you have a large archive of movie DVDs, which you have purchased legitimately, and you would like to keep duplicate copies of them. If you just place the discs in a DVD writer directly and trying to create duplicates that way, you probably will not succeed due to the encryption mechanisms embedded into the discs. Most of the so-called “one click DVD copying” softwares I have tested do not work, or the quality of finished disc is simply terrible.
First, you will need to remove the encryption mechanism known as CSS (Content Scramble System).
There are many DVD decryption softwares available on the internet, and most reliable ones are DVD Decrypter and DVDFab Decrypter. What the decryption software does is to remove copy protection from all the files within the DVD, typically about 4.5 GB, and save them onto the computer’s hard drive.
In most movie DVDs, there are only two directories in them. One is “AUDIO_TS”, which is usually empty. The other is “VIDEO_TS” which has many files with extensions including .IFO, .BUP, and .VOB. The .IFO files are DVD information files, which stores information about chapters, subtitles, and audio tracks. BUP files are just backups of IFO files. VOB (DVD Video Object) contains the actual video and audio contents.
Once the encryption is removed, you are now able to use any DVD writing software (i.e. Nero) to copy these decrypted files onto a recordable DVD disc. By keeping all the files in the VIDEO_TS directory, the duplicate would play just like the original DVD including those annoying FBI and MPAA warnings.
Related: Frequently Awkward Questions for RIAA and MPAA, RipIt4Me, AnyDVD, CloneDVD, DVD Shrink