Re: Ok, so you have fixed some bugs
Youtube downloader add-on (or video download helper add-ons) are quite 'last decade' now: there are plenty of websites which allow you to do that quickly for Facebook, Twitter, Youtube videos. Even the more obscure ones hosted on Chinese video sites.
Some of the browsers already have a built-in ad blocking feature. You can even enable it on Incognito (private browsing) mode.