Youtube troubles in Linux

When I tried to watch a video in YouTube of an elephant painting itself, it didn't work. After downloading it with the great Firefox addon Download Helper and trying to listen to it, it still didn't work. Even worse, totem movie player advised me to buy some codecs for 16 euros. Realizing that once again Fedora wanted money for codecs that are supposed to be free, I googled for the codecs that playback required. Turns out that ffmpeg will easily change from an flv to an mpg. This page shows you how. It worked, but now there was no sound. Oh well. I'll keep trying.