国外的这个文章很牛:(http://www.ubuntugeek.com/install-mplayer-and-multimedia-codecs-libdvdcss2w32codecsw64codecs-in-ubuntu-904-jaunty.html) Install libdvdcss2 and w32 video codecs in Ubuntu 9.04 (Jaunty)
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.
For Ubuntu 9.04 (Jaunty) Users use the following procedures
sudo wget http://www.medibuntu.org/sources.list.d/jaunty.list --output-document=/etc/apt/sources.list.d/medibuntu.list
Then, add the GPG Key using the following commands
sudo apt-get update
For i386 Users install Codecs using the following command
sudo apt-get install medibuntu-keyring
sudo apt-get update
sudo apt-get install w32codecs libdvdcss2
Foramd64 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