EDIT:
Dont know why but today it started to work again, then I change from 1 star to 5 stars:). Hope it will not change tommorow:).

OLDER:
It was great addon. It was one of my corre addons in firefox. i am still on 56.0.2 (64 bit) firefox version. It worked great (stoped working in 2019), but now I dont have this function even i did not update firefox or this addon (it says it is still version 0.8.2017061501 (which is for a <57 firefox version). Also can not fin anywhere this version to reinstall it. It is very big loss for me, as i dont want to move to new versions and now I lost funcionality i use every day up to today :(. I would put 5 stars if it would work (or my problem would be solved)