If you want to watch Divx embedded Videos in your browser, like they used to be offered by Stage6, you can use the mozilla-mplayer package with the following customizations:
Install the package mozilla-mplayer.
In /etc/mplayerplug-in.types you need the lines
video/divx:divx:DivX Media Format;
video/vnd.divx:divx:DivX Media Format;
and in /etc/mplayerplug-in.conf you need the line
Don't start your browser before you've made these changes, otherwise you need to uninstall the plugin, start the browser, exit it, reinstall the plugin and then it should work. This works in Opera and Firefox for me.
Update: Unfortunately this does not work on all pages, some seem to check specificly for the divx.com plugin, which of course won't work...