“DVD region code” is a feature that is integrated into DVD players and DVD video discs that doesn’t let you watch a DVD video if your drive’s “region code” doesn’t match with the DVD disc’s region code.
There are 6 DVD regions that cover various countries/territories globally. For instance, if you purchased a DVD drive in Japan and tried to play a DVD video disk that’s originally from US, then the DVD drive won’t let you play it. However the DVD drive manufactures do let the users change between region codecs 5 times (usually). But once you’re done changing the code 5 times, your drive is locked and cannot change region codes anymore!.
Now if you use Windows then you can easily change the DVD region value using the “device manager” but it is a little difficult under GNU/Linux.
So as an Ubuntu user, if you want to change the DVD region code of your DVD drive then try “regionset”. It is based on the command-line but is very easy to use.
You can install “regionset” in Ubuntu 12.04 Precise Pangolin, 11.10 Oneiric Ocelot, 11.04 Natty Narwhal, 10.10 and 10.04 by using the below command in your Terminal window.
sudo apt-get install regionset
An example …
First insert a DVD disc into the drive. Then enter the below command in your Terminal and regionset should automatically detect your DVD drive.
regionset
When asked, confirm by typing “y”. And then enter the correct DVD region code that you want to use.
Then it’ll ask for your final conformation.

That’s it.
If you have more than one DVD drive, then simply enter the device path as shown below.
regionset /dev/dvd
Simply replace your drive path with “/dvd”.
Read this Wikipedia article to get a full list of Region codes and their appropriate countries. You might wanna visit this Regionset home page for additional information as well. But as said before DVD drive will only let you change between 5 region codes and after the 5th, it’ll be locked into that region code. So be very careful while using it.
If you want to change between unlimited instances, then you can do so by downgrading your DVD drives’ firmware from RPC-2 to RPC-1. However this means that you’re flashing the chip of your DVD drive and you might end-up permanently damaging it!. So use it with caution (Google “RPC-1” for learning how to do that).