Play Yahoo! Launch Videos in Firefox and Linux
Yahoo Launch doesn't work in Firefox. It also doesn't work with linux. This tutorial will fix both of these problems in a few simple steps.
Make it work in Firefox
There is an extension that you can install that will allow you to play videos. Download it here and install it.
Make it work in Linux
This is taken from my Kubuntu guide. You'll need to install mplayer and mplayerplug-in, but these don't install correctly from the package manager in Ubuntu. Instead, download the installation file from this site, and follow the instructions. I did a network install, and make sure you select all the options you need (all the codecs and the mplayerplug-in, especially).