Update 2024/DEC:
Unfortunately, no longer works. :(
(Even the payed version.)
I sincerely hope you will be able to fix the extension. I will update this review to five stars as soon as that happens!
<3

Update 2024/APR:
Still a great, great, great add-on!! Still loving it! :)
I was happy to make a donation, and will donate again.

Update 2022/NOV:
still loving this addon!
Doing exactly what it is supposed to.
You can also download just MP3s.
Keep up the good work!

Add-on actually works. :) As of 05/AUG/2019
In the free version, you can download 360p MP4s. After a one-time payment, higher quality videos and mp3s are available. VERY WELL WORTH IT! Excellent add-on!
Thank you so much!
Lazar