Worked fine for years, but now I'm getting ads about "Mac Virus & Adware Removal by www.y2mate.com" occasionally.

why this add-on collect all website data when it's should be only youtube website?

VERY GOOG.

Very good app

Fantastic addon. Adds a download button just below your video. Also allows you to select the quality you prefer to download. So you can download in 1080p. I have tested 4k or 8k yet.

Note to the developer: you should try to make this compatible with this extension: https://addons.mozilla.org/en-US/firefox/addon/enhancer-for-youtube