How to easily convert webm video to mp3 format?

Webm to Mp3 converter - Recently I screencast my Fedora linux desktop. The screencast will be saved in webm format. If you are using latest Fedora with Gnome 3 you mind have seen it. Now I had an problem where most of the online and few offline video editing tool were not able to recognize webm format. The popular video format I know is mp4.

Tried several online conversion website - It failed

I Google'd for online video editing tools. I tried the top results. Video upload was successful but conversion failed. Repeated for several times but it failed again.

I don't want to install software to make this simple conversion. Out of the blue I got an idea.

Upload to YouTube and download it 

I downloaded several YouTube video which will be always in mp4 format. The idea forced me to do a try. I uploaded and ‎downloaded it from online YouTube downloader. Boom video got converted.

Link for YouTube video down loader - http://en.savefrom.net/

I usually use above website to download YouTube videos. It won't ask you for Java plug-ins whereas other website ask for it. To download copy the link of your published YouTube video and paste it in the download bar.