the easiest way to do it and add several other items you will need is
to get "Automatix"

http://www.getautomatix.com/

I was in a total pickle till I got that it's really easy to use and it
works

Unbuntu needs additional codecs installed to play WMV or AVI files.
Here's a page which offers a good explanation of how to do that:
http://ubuntuforums.org/showthread.php?t=75278

You need to install the win32 codecs, assuming you are running 32bit
Ubuntu. If you are running 64bit Ubuntu then you need the win64 codecs.

Open a terminal and type the following:

sudo -s

Then, type your password to go root. Next, follow the directions below:

wget -q medibuntu.sos-sts.com/repo/medibuntu-key.gpg -O - | sudo
apt-key add -

sudo wget medibuntu.sos-sts.com/sources.list.d/dapper.list
-O /etc/apt/sources.list.d/medibuntu.list

sudo apt-get update

Then...assuming you are running 32bit Ubuntu type:

sudo apt-get install w32codecs

Also, see this page for instructions on how to make Ubuntu play all
media formats:

https://help.ubuntu.com/community/RestrictedFormats

you need to install the win32 codecs, install totem xine, and update
your libxine1. your can do that from the package manager. ulternativly
you can upgrade to ubuntu 7.04 it has a better handeling for codecs.

Go to: automatix.com and use the easy install for your distro. Install the
codecs. Mine works seamless.

VMANN: you should get VLCPLAYER, imo.
go here:
http://ubuntuguide.org/wiki/Ubuntu_dapper
tells you how to install all sorts of cool stuff. none of which you will
find in "the official ubuntu book." in fact, the link you are referred to
in that book is a DEAD link. heh.
http://ubuntuguide.org/wiki/Ubuntu_dapper#How_to_install_Multimedia_Player_.28VL\
C.29_with_plug-in_for_Mozilla_Firefox
that's the link directly to HOW TO INSTALL VLC. there's shit about totem in
there too. be sure to install codecs, which function to make your player(s)
work with various file types, and i think improve quality as well.