This extension is very nearly perfect. It has worked for me tremendously in the 6 months I have used it.

However, a few small issues keep it from being a 5 star.
Some websites have issues downloading and it will only download a small portion of the video, other times websites will give errors and not work.
And some videos will download at a very slow speed in comparison to a video that was just downloading much faster.

Although these issues are minor, they do compound to make it somewhat annoying at times and I hope to see them fixed or at least improved upon, because this extension is a lifesaver.