Seems to do a good job at blocking many things; however when used in conjunction with Ad Killer, it disables the The menu selection (The notification bell, search bar, home menu, user icon, upload icon, YouTube Apps icon, etc). I have about a dozen other items in use with it right now; when I took Ad Killer off and restarted FireFox, I got the Menu bar back; however one other functionality remains missing that I know will come back if I disable this particular app--but with this app and no others enabled I do NOT lose this functionality. That functionality being the ability to start a conversation thread on a Video. I haven't figured out which combination of apps is causing this problem yet. (Lesson to learn: This app is great, but does not play well with certain other apps.)