UPDATE October 20, 2022
Add-on no longer works. Only attempts to redirect to a site that I cannot reach. according to some looking around, this is a site to avoid at all costs. I think I'm done returning to this add-on again and again. Do not use. I am also going to report the add-on.

UPDATE Oct 10-22:
You *MUST* use a strict pop up blocker add on and deny the page from opening any pop up windows. When clicking the "Download MP3" button, you will get a pop up. Also the first click after refreshing the page, and every other click with a gap of 10 seconds anywhere on the page. These pages will be everything from "adult content" pages to fishy/phishy add-on advertisements.
Not every click on the green button will work to start the download either. You may need to refresh the page.

Update: Is working again. Simply click the "MP3" button next to the view count on the video, click your desired bitrate on the next window, and done!

Hasn't worked for a little while now. Downloads a 0KB file. Last checked: 08-24-21, 10P GMT