Does what is says, but a CPU hog, even when not on a YouTube page Rated 3 out of 5 stars
It's a good add on, but for a while I noticed that Firefox was constantly using at least 20% of my CPU -> ALL THE TIME. I finally tracked down the problem by disabling this add on. What's weird is that this add on would constantly use 20% of the CPU even if there were no YouTube videos on the page. Try it -> just go to any page like the Google homepage while you have this add on enabled, and watch your CPU monitor. I have no idea what this add on is using the CPU for when there are no videos to download, but I'd rather not have the processor wasting power and speed for no reason. Now I just selectively enable this add on only when I want to use it. Also scroll down see the review by popu on September 16, 2013. Same problem. I'm running Firefox 24.0 on Mac OS X 10.8.5.This review is for a previous version of the add-on (220.127.116.11-signed).
This issue will be fixed on the next update (2.1.8).
Sorry for the inconvenience.