It has been updated, after a long period with no updates; it's now finally at the same version as the Google Chrome version.
It provides a lot of great features, which make interacting with Youtube a lot less addicting, frustrating and annoying. Besides allowing you to set limits on Youtube watch it includes toggles for hiding or changing most of the parts of Youtube — which are the parts I find the most useful. It seems to be working without issues, which is great to see.
It's great, I love it, and I'm so glad it's back.