I glad to here you can actually play embeds
with mozilla. I suppose not with a Kubuntu/Ubuntu
Dapper install as others have verified they wont play
using mplayerplug-in but will play with gxine. Boy,
this is one difficult issue to resolve. Most likely,
it will be something simple if I every find the
solution.
Thanks for the suggestion and I'll keep trying.

Leonard, what is the reason for that you do not want to install it from mplayerplug-in cvs ? I am running Dapper myself and using mplayerplug-in cvs is really not problem at all. It works great with both Firefox and Mozilla.

This is what I did:

Make a directory to keep what you are going to install a little bit organised
mkdir ~/apps

Go there
cd ~/apps

Install cvs
sudo apt-get install cvs

cvs - d:pserver:anonymous@cvs.sourceforge.net:/cvsroot/mplayerplug-in login
(just hit enter for password)

cvs -z3 -d:pserver:anonymous@cvs.sourceforge.net:/cvsroot/mplayerplug-in co mplayerplug-in

Install some needed libs and packages (perhaps you need more ?)
sudo apt-get install libgtk2.0-dev gettext libxpm-dev mozilla-dev build-essential

Get Gecko
wget http://ftp.mozilla.org/pub/mozilla.org/mozilla/releases/mozilla1.7.8/gecko-sdk-i686-pc-linux-gnu-1.7.8.tar.gz

Unpack it
tar -xzvf gecko-sdk-i686-pc-linux-gnu-1.7.8.tar.gz

Get into the mplayerplug-in directory to start building
cd mplayerplug-in

Configure it. Swap your paths for mine
./configure --with-gecko-sdk=/home/rune/apps/gecko-sdk --enable-gtk2

compile it
make

"install it"
make install

Copy all the plugins files to mozilla and firefox locations
cp mplayerplug-in*.so /usr/lib/mozilla-firefox/plugins
cp mplayerplug-in*.so /usr/lib/mozilla/plugins
cp mplayerplug-in*.xpt /usr/lib/mozilla-firefox/components
cp mplayerplug-in*.xpt /usr/lib/mozilla/components
cp mplayerplug-in.types /etc
cp mplayerplug-in.conf /etc


--
Rune Baggetun