If you are just getting started in Ubuntu, I highly recommend that you check out my other guide "Ubuntu: Getting Started". It will help you get started in the basics of Ubuntu. That said, onto the instructable:

Ubuntu is a great OS, but one issue is that DVD decryption is not included by default because of legal reasons. DVD decryption allows you to watch DVD movies on your computer. In order to get DVD decryption, we need to install the restricted formats file. The restricted formats file allows you to read DVD's and do certain other things that you wouldn't be able to do by default.

This instructable is for ubuntu 10.04+, so if you are you a version of ubuntu earlier than 9.10, you will need to visit this website: https://help.ubuntu.com/community/RestrictedFormats/PlayingDVDs

Step 1: Open the Terminal

For this install, we will be using the terminal. By following my instructions, you will be able to watch and play DVD's on your computer.

First, enter this command:

sudo apt-get install libdvdread4

This command puts the necessary files on your computer to read the DVD's, now we need to enable them.

Now enter this command:

sudo /usr/share/doc/libdvdread4/install-css.sh

This command installs and enables the previous command. We now have the files installed, but we aren't finished yet.

Step 2: Reboot

Rebooting will allow the changes we made to take effect. While your computer is rebooting, go grab a DVD to test.

Step 3: Test

Put the DVD into your computer. The DVD should show up on your desktop. Right click on it and click "open with >". Select your movie player and test. If you don't have a movie player, I have a few recommendations:

I personally use "Movie Player". It came pre-installed on my version of Ubuntu and it works fine.

I have heard a lot about "Xine". If you don't already have it, you can download it by using the Ubuntu software center.

Step 4: Watch a Movie.

We have now finished enabling DVD playback on our Ubuntu system. I hope this has helped you. If you still cannot play DVD's, your hardware may not support DVD playback, or your system may need drivers to work with your DVD drive. Go to www.ubuntuforums.org to get some help with any technical advice or assistance you need if the DVD's don't work after you have tried the steps above.

Have fun, watch a movie, and enjoy linux. I also suggest that you hook up a nice pair of computer speakers with a subwoofer for the best home-theater experience of your life. Transformers with a good sound system is AMAZING!!!

Thanks for reading my instructable, I will be making a few more of these in the near future.