There is no extension. It just redirects to a website.

Works better than I expected. Downloads YouTube videos pretty quickly and the interface is simple. I like that it doesn’t spam ads or make Firefox feel slow while using it.

So far it's as good as advertised. It's a little more involved than a download button, but hardly difficult, and the selection of download options are nice. I'm glad I found this one. I am giving it 4 stars as I've yet to use to for a long period of time. So far it's great though.

This is by far the best YouTube downloader I've found. It works much better than all the unofficial options I was using. Highly recommend!

Great app very interesting

So many youtube downloaders out there and this is the only one that works for me. And it has HD. Amazing!!