This is an overall "mediocre" video downloading program.
The biggest issues that I have with this add-on were deal-breakers for me.

1. Unable to download: far too often I would attempt to download a video, only for the downloader to tell me "This video cannot be downloaded". The kicker, is that I tried it out and had it happen numerous times on videos that were royalty free and videos that I'd had no problem downloading with other video downloaders in the past. Unacceptable, absolutely unacceptable to have a video downloader that won't download the videos I want. Frankly, ONE instance of this happening is too many.

2. Duplicate downloads: I've come across several instances where I would try to download multiple videos (not at the same time, one after another mind you) and after the initial video is downloaded without any problems, I go to download the next video and the next, etc. The UI indicates everything is working as it should and I'm downloading the videos, except that it isn't. I go to check the file directory where I downloaded the videos to, and they have the names assigned to them, everything seems to be in order, up until I click on and play the videos. The downloads are all duplicates of the first video!

3. Not recognizing that there's a video to download: This one is hilarious, especially given what the add-on authors advertise this add-on as being. Sure enough, time and time again the add-on will fail to activate because it can't tell that there's a video available to download.

ridiculous, absolutely ridiculous.

Two stars, because when it actually works, its great; too often it doesn't work as advertised.