So, you figured out how to use Video Download Helper to download videos from YouTube and now you want to listen to the audio on your MP3 player. This simple tutorial shows how to use free software to extract the audio track from a FLV and save it as an MP3 file.
While Video Download Helper can do some conversions on-the-fly, it is not particularly suited for our specific purpose. Our conversion tool of choice is ffmpeg. Here is how we use it:
ffmpeg -i YourDownloadedFLVFile.flv -f mp3 -vn -acodec copy YourExtractedMP3Content.mp3