I've been using the extension for years. Its great. The only complaint is that i bought it for chrome. Found out, after the fact, it couldn't download YouTube videos on chrome. So, I decided to use it on Firefox, and it turns out it requires separate licensing. So, basically, you have to buy it twice.

And, unlike most of the 1-star reviews, I don't think there is anything wrong with paying for a useful service, but I think having to pay twice because you are using a different browser (especially because I just would have got for Firefox in the first place if I knew I couldn't download YouTube videos on chrome) is a little much.