Here are the extensions I installed:
You want to install flash player. In Ubuntu, use Synaptic to install adobe-flashplugin. You may also want to install RealPlayer from real.com and/or the open source helix player.
Import the bookmarks and Adblock Plus rules you exported earlier, and paste the contents back into Informenter.
I find that Firefox does not sense that you are connected in Ubuntu. You must disable "Work offline" in the File/ menu of Firefox each time you start it up. I did not have that problem with Debian. You may not have the problem if you do not use a plain modem to connect to your ISP.