MPlayer is a movie and animation player that supports a wide range of 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 MX/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- based subtitle formats too. For video output, nearly every existing interface is supported. It’s also able to convert any supported files to raw/divx/mpeg4 AVI (pcm/mp3 audio), and even video grabbing from V4L devices.

Install Mplayer in Ubuntu 11.10 (Oneiric)

You have to make sure you have enabled universe,multiverse repositories

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

or Click on the following link

apt://mplayer

Install w32 video codecs and libdvdcss2 in Ubuntu 11.10

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.To play encrypted DVDs, the libdvdcss2 package is essential.

The following command adds Medibuntu’s repository to Ubuntu. It also adds Medibuntu’s GPG key to your keyring, which is needed to authenticate the Medibuntu packages.

sudo wget http://www.medibuntu.org/sources.list.d/$(lsb_release -cs).list --output-document=/etc/apt/sources.list.d/medibuntu.list

sudo apt-get -q update

sudo apt-get --yes -q --allow-unauthenticated install medibuntu-keyring

sudo apt-get -q update

You may also wish to add the following packages. The first will cause many apps from the Medibuntu repository to appear in Ubuntu Software Center (Ubuntu 9.10+) or Add/Remove Applications (versions prior to 9.10). The second will allow users to generate crash reports against Medibuntu packages and submit them to the Medibuntu bugtracker.

sudo apt-get --yes install app-install-data-medibuntu apport-hooks-medibuntu

Please note you may have to use --force-yes instead of --yes in order for this command to succeed.
For i386 Users install Codecs using the following command

sudo apt-get install w32codecs libdvdcss2

For amd64 Users install Codecs using the following command

sudo apt-get install w64codecs libdvdcss2

Using above download locations you can install most of the mutimedia codecs for ubuntu.

Mplayer Plugin for Firefox

If you want to install Mplayer with plug-in for Mozilla Firefox run the following command

sudo apt-get install mozilla-mplayer

or click on the following link

apt://mozilla-mplayer