Mplayer is a popular movie player for Linux that supports reading from network and a wide range of codecs.
Install Mplayer:
Install mplayer in ubuntu karmic is very easy, just need one command in terminal(Applications/Accessories/Terminal):

sudo apt-get install mplayer

Then you can launch this from Applications—>Sound&Video—> Mplayer Movie Player.

Install libdvdcss2 and w32 video codecs:
You need to install w32codecs for playing WMV,RealMedia and other formats files and libdvdcss2 for playing encrypted DVDs.
Use following command to add Medibuntu’s repository.

sudo wget \

Add the keyring:

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

Install codecs:
for i386 user:

sudo apt-get install w32codecs libdvdcss2

for amd64 user:

sudo apt-get install w64codecs libdvdcss2

If encounter:“ Error opening/initializing the selected video_out(-vo) device.”
Try this:
Right click on mplayer window,select “Preferences”.In Video tab/Available drivers,choose “xv”(or try other drivers) and click OK.Log out and back in,and mplayer should work now.