for those who use firefox quantum: extension still works, but...

1. you have to switch to new youtube format/layout
2. maybe you will need to clear cookies that contain "google" and "youtube" from your browser first

i noticed that some parts of youtube server are different from the new layout so video blocker won't work on them, but if you're watching your favourite content, the right pannel with suggested videos will be filtered with video blocker rules, the same as with search results on the main page, so that means this extension is still useful.