This used to be a brilliant add-on. I don't know if it's because of upgrades and changes to Firefox, YouTube/Google, or Windows, but it's become a total resource whore. Blocking more than a few YouTube channels sends Disc usage to 100%, memory goes through the roof - up to 97% - and my computer freezes completely until I go to Task Manager and end Firefox which is eating all the memory it can. I can watch it going from, say, 111MB and slowly climbing to up past the 2,900MB mark. YouTube give me there error message saying a Firefox app is the problem. Video Blocker is always the culprit.