Did you install the restricted extras for Ubuntu? These are proprietary
codecs and drivers that are not included with the distribution, but are in
the repositories.

You can install them from Synaptic, Add and Remove or from the command line.
In Synaptic search for restricted-extras and choose ubuntu-restricted-extras
or kubuntu-restricted-extras, etc.
In a terminal you can also use: sudo apt-get install
ubuntu-restricted-extras

They give you flash, windows ttfs and multimedia codecs such as libdvdcss2
which allows you to play movies.