Most commercially produced movies released on DVD are encrypted. The original purpose of this was to reduce piracy. Today however it is mostly an inconvenience for consumers. In order to play these discs you need to install a library that enables decryption.
The entertainment industry has attacked free software developers and distributors in the past. There have been a number of well known cases. As a result these libraries are not included in most distributions. If it is legal (consult a lawyer if needed) where you are this is the procedure to install the required software:
1. Open up a terminal
2. Enter the following commands and hit enter (enter your password and accept the installation when prompted)
sudo apt-get install libdvdread4 regionset vlc
sudo ln -s /dev/scd0 /dev/dvd
If this is a new computer you may need to set the region code as well. Region codes allow the entertainment industry to charge different prices in different regions of the world. This prevents you from playing a disc sold in another region. Until this code is set you can't play DVDs from any region.
Enter the following code:
There are a limited number of times you can change the region code. It will eventually be locked permanently. Enter your password and answer the questions when prompted.
Enter the region below where you live:
REGION 1 -- USA, Canada
REGION 2 -- Japan, Europe, South Africa, Middle East, Greenland
REGION 3 -- S.Korea, Taiwan, Hong Kong, Parts of South East Asia
REGION 4 -- Australia, New Zealand, Latin America (including Mexico)
REGION 5 -- Eastern Europe, Russia, India, Africa
REGION 6 -- China
REGION 7 -- Reserved for Unspecified Special Use
REGION 8 -- Reserved for Cruise Ships, Airlines, etc...
REGION 0 or REGION ALL -- Discs are uncoded and can be played Worldwide, however, PAL discs must be played in a PAL-compatible unit and NTSC discs must be played in an NTSC-compatible unit.
3. Start VLC; other DVD players may work as well although some may require additional steps