How to Download YouTube videos as mp3 with Addoncrop
Top 8 YouTube to MP3 Add-ons for Firefox
12 Best Free YouTube to MP4 Converters - Wave.video Blog: Latest Video Marketing Tips & News | Wave.video
Firefox add-on that allows MP3 conversion for free, video conversion, audio extraction from video, video and audio combining, multiple videos combined into one, maximum volume adjustment, video resolution change, video rotation, sound
YouTube To Mp3 Converter | YouTube Downloader – Get this Extension for 🦊 Firefox (lv)
Top 8 YouTube to MP3 Add-ons for Firefox
Youtube to MP3 Converter Free – Get this Extension for 🦊 Firefox (en-US)
Media Converter :: add0n.com
Advanced Youtube to MP3 converter extension - Opera add-ons