MPlayer: A
movie and animation player that supports a wide range or codecs and file formats, including MPEG 1/2/4, DivX 3/4/5, Windows Media 7/8/9, RealAudio/Video up to 9,
Quicktime 5/6, and Vivo 1/2. It has many MMX/SSE (2)/3DNow(Ex) optimized native audio and video codecs, but allows using XAnim’s and RealPlayer’s binary codec plugins, and Win32
codec DLLs. It has basic VCD/DVD playback functionality, including
DVD subtitles, but supports many text-baased subtitle formats too. For video output, nealy every exising interface is supported. It’s also able to convert raw/divx/ mpeg4 AVI (pcm/mp3 audio), and even
video grabbing from V4L devices.
You need to add the following lines to /etc/apt/sources.list file or you need to make sure you have enabled Universe and multiverse repositories in /etc/apt/sources.list file
gedit /etc/apt/sources.list
enter these two lines and save your file
deb http://archive.ubuntu.com/ubuntu gutsy universe multiverse
deb-src http://archive.ubuntu.com/ubuntu gutsy universe multiverse
Now you need to run the following command to update the source list
sudo apt-get update
Install mplayer using the following command
sudo apt-get install mplayer
if you want to Open Mplayer just type
gmplayer
or
You can Open from Applications—>Sound&Video—> Mplayer Movie Player

Once it opens you should see the following screen

Installing libdvdcss2 and w32 video codecs in Ubuntu Gutsy Gibbon
Support for WMV, RealMedia and other formats has been bundled into the w32codecs package. This package is not available from the Ubuntu repositories due to licensing and legal restrictions.
For Ubuntu Gutsy Gibbon Users run the following command
sudo wget http://www.medibuntu.org/sources.list.d/gutsy.list -O /etc/apt/sources.list.d/medibuntu.list
Now you need to copy the key using the following command
wget -q http://packages.medibuntu.org/medibuntu-key.gpg -O- | sudo apt-key add -
Update the source list using the following command
sudo apt-get update
Install Codecs using the following command
sudo apt-get install w32codecs libdvdcss2
Using above download locations you can install most of the mutimedia codecs for ubuntu.
sudo apt-get update
Mplayer Plugin for Firefox
If you want to install Mplayer with plug-in for FireFox run the following command
sudo apt-get install mozilla-mplayer
:)
Another Way(Gui)
Configuring Synaptic Package Manager for installing MPlayer
To install MpPlayer on Ubuntu you will need to change the default repository settings of SPM as MPlayer is not contained in the default repository. To do this you will need to open the Synaptic Package Manager and you can do this via the System menu. If you haven’t changed the default Desktop of Ubuntu then the System menu can be accessed at the top left of your screen:

If all is good you will be prompted for a password.

Here you must enter your password (the same one you use to log into the system). If you don’t know the password then you have a problem and its probably caused by the fact that the computer you are using is not yours. In this case you have to find the computers owner and ask them for the password (which is usually not polite unless you know them well) or ask them to input the password while you look casually in the other direction.
Assuming the password entered is correct – you will now see the SPM open infront of you. It may be that you first see the following ‘Quick Introduction’ (this appears if you haven’t used SPM before).

Just click Close and move on. Lets look at the Synaptic Package Manager interface…

Lets not worry about the details of the interface for now. All we want to do is change the repository settings. To do this click on the Settings and choose Repositories

Now we get to where we can do some business. You should already have Canonical-supported Open Source software (main) selected :

Make sure that Software restricted by copyright or legal issues (multiverse) is checked :

Also make sure that Community-maintained Open Source software (universe) is also checked.

Now close that window by pressing the big close button at the bottom right.

Next, you will see a warning telling you the repository has changed :

Click the Close button and move on to SPM so you can refresh the repositories as the warning suggests. To do this, do as the warning says – click on Reload :

You should then get some feedback saying the repositories are being updated and showing the progress.

Installing MPlayer with Synaptic Package Manager
Now the real business. Its pretty easy. Click on the nice big Search button:

The search window will open and now enter ‘mplayer’ in the field:

Great. Now press Search at the bottom right of the above window. The search should not take very long and when it is complete you will see mplayer listed :

If you highlight mplayer (by clicking once on the name) you will see some information about mplayer displayed :

Now you can read the information if you wish but there is nothing critical there. Best thing to do is just to double-click on mplayer. By doing this you are ‘marking’ (choosing) the software for installation. If you do so then an additional window appears:

Now click Mark:

You have now told Synaptic Package Manager that you want to install MPlayer. If all is well then the package will be highlighted (if you click on another item you will see that MPlayer is marked in another color):

Now press the Apply button with the nice big tick next to it :

Next SPM informs you of how much space will be taken by the installation :

Now you can just click Apply at the bottom right of the screen and the installation will start. A progress bar will be shown:

When completed (downloading and installing) you will have this screen :

That means all is well. Pat yourself on the back and press Close. Synaptic Package Manager will then return to its original state. Close it :

Now you can open MPlayer…just browse to the Applications menu, choose Sound & Video, select MPlayer and release the mouse :

Enjoy
:)
Happy Ubuntuing