This extension no longer works at all. Look for BlockTube! That's kept current and you can block any keywords you want!
https://addons.mozilla.org/en-US/firefox/addon/blocktube/
In BlockTube settings, simply put every word on a separate line, and it will block every video with that word in the title. I had to search for an hour to find BlockTube, but it was totally worth it!!!

Let the developers of Video Blocker know that it no longer works, and maybe they will try to fix it.