Since most Apple media players like iTunes mainly use MPEG4 (or MP4) for videos, playing DVDs on iTunes is a problem as its movie files aren't in that format. You need to have an MPEG4 version of the DVD video to play on iTunes. Some DVDs are now sold with an iTunes Digital Copy option, which allows you to download an iTunes compatible copy of the DVD direct onto your iTunes application. If your DVD doesn't have iTunes Digital Copy, you need a program that will make an MPEG4 copy of the DVD to load into iTunes.
Open the iTunes application on your computer. Insert the DVD into the DVD drive. If it has iTunes Digital Copy, the disk will appear in the left side of the window under "Devices."
Click on the disk in the left-side list and it will appear in the main screen with an "Enter Code" text box. Input the serial number from the DVD in the box and click the "Redeem" button. When the dialogue box asking for it appears, enter your Apple ID and password.
Go to the "Downloads" selection in the Store list to track the download process; you can see it on the status bar. Once it's finished downloading, you can open the video from the "Movies" selection in the Library list.
Download a DVD ripper program like Xillisoft or Handbrake or Xillisoft and install it on the computer. Make sure the program can convert video into MPEG4. Open the application and load your DVD into the disk drive.
Import the DVD's main movie file into the ripper program by selecting the "import" command, going to the drop-down list and opening the folder with the DVD files. The correct file will be the largest one with longest time period.
Choose the file format to convert to from the program's output or destination window. Select an MPEG4 or MP4 format, or one with "iTunes" or "Apple TV" in the name. Go to the codecs or audio format drop-down menu and select a similar format.
Select a destination on the computer to save the MPEG4 file to, be it the desktop or a folder. Depending on the program type, you will either browse another drop-down list of destinations or type in the full path name beginning with the drive (as in C:).
Click the "OK," "Rip" or "Convert" button (it could also be a DVD icon) to save the file in an MPEG4 format.
Open up iTunes program and add the MP4 file with the "Add to Library" command or by by dragging it to the main list screen.
An encrypted DVD will require a ripper software program that can decrypt the movie file. The legality of ripping an encrypted disc, even for personal use, is highly doubted and constantly debated