You should install the required codecs. I can't say exactly what package to install because I can't access a Ubuntu 6.06 box. Try opening the Synaptic Package Manager and search for gstreamer-plugins or gstreamer extra codecs (it could be packages like gstreamer-plugins-extra or gstreamer plugins ugly or so).
install libxine-extracodecs and the require gstreamer plugins
BTW, both MPlayer and VLC Player are able to play YouTube .flv files.
Last edited by SkyEye; 10-31-2008 at 06:04 AM.