this plugin will enable you to encode your videos into Google's VP8 WebM which is supported by chrome,Firefox6,IE9 with addon and HTML5 players.
check the readme.txt inside the folder.
you need a linux server with terminal access ssh to install the latest ffmpeg and php-ffmpeg.
this plugin is a modified version of http://niroshanfernandez.wordpress.com/2010/02/08/hello-world/
i just changed flv into webm so ffmpeg enocdes to VP8 Video instead and added the right Meta-type
future updates would be to add progress bar while encoding takes place