Converting flv into mp3...?
FREE program to use to convert FLV videos into MP3 audio files.

Try "Any Audio Converter" which can be downloaded from any-audio-converter.com It has the advantage of not only extracting audio (MP3 as well as WMA, AAC and OGG) from FLV video, it also extracts the same audio formats from MP4 and WMV (Windows Media Video). And it's freeware (they have a "professional version" as well--just click on the free version download link).

The same people also produce "Any Video Converter" which will download the high quality versions of FLV video from youtube. It will also convert between virtually any video formats you'd ever want (e.g., FLV to MPEG/MP4/WMV/AVI/etc. and vice-versa or mix-and-match however you like). Again, they have a professional version, but just click on the free version link that's on the same page.

The names may sound corny, but the programs work well.
Source(s):
http://www.any-audio-converter.com
http://www.any-video-converter.com