How to Convert a FLV to MP3 on a Mac
- 1). Visit a website like Freefileconvert, Media-convert or Convertfiles.com (see "Resources" for links).
- 2). Click on the "Browse" button to bring up a window. Double-click on your FLV file inside of the window.
- 3). Click on the "Output Format" menu and select "extract audio only .MP3" from the list of options.
- 4). Click "Convert." Click the new link that appears to download your new MP3 version of the FLV video.
Source...