Doesn't work anymore. (Jun/2021). It worked around 2020, but no more.

good but please post the source code on github/gitlab I only trust open source browser addons

This is not working.
Firefox 72.0.2 on MacOS

Worked great the first week now it's not working some of the time

10-3-2020 doesnt work for me anymore unfortunately :( pity bc it is a really nice addon, I hope it gets repaired soon