SUPER © is a free media encoder which handles Flash FLV files as well as many other formats. It is basically a front-end GUI to various open-source encoders (ffmpeg, mencoder, mplayer, x264, mppenc, ffmpeg2theora & the theora/vorbis RealProducer plugIn). All the necessary codecs are built-in.
This is a handy utility to have. Despite some limitations and slightly strange behaviour we recommend it.