In order for this add-on to work after you've installed it, you'll need to make sure you clear your cache.

Click:

1) 3 bar "hamburger" menu
2) "Library"
3) "History"
4) "Clear recent history"
5) Make sure that "Cache" is selected, indicated by a check mark.
6) And make sure that "everything" is selected for the time range.

Enjoy old twitter!

Edit: Copy and paste doesn't work.