<p>Make sure you have the "ubuntu-restricted-extras" package installed, and if that doesn't work, try installing the "kubuntu-restricted-extras" package too.</p>
<p>On the command line, type the following:</p>
sudo aptitude install ubuntu-restricted-extrassudo aptitude install kubuntu-restricted-extras
<p>You'll be asked for your password. You might also need to update your repository information first by typing in:</p>
sudo aptitude update