Good

Really fast and simple to use downloader. Thanks :)

parfait

While every other downloader needs you to install dubious software from who knows where, this one just needs you to click a button. It is simple, easy and efficient.

Since I am rating it low, I will explain.

Sometimes it does not download the video.
For example the following does not work:
https://www.youtube.com/watch?v=LPxIssabhTc

Sometimes it downloads at 360p, although the video is playing at 1080.
Example:
https://www.youtube.com/watch?v=sIaT8Jl2zpI

As the following page states:

https://support.mozilla.org/en-US/kb/permission-request-messages-firefox-extensions#w_access-your-data-for-all-websites

"The extension can read the content of any web page you visit as well as data you enter into those web pages, such as usernames and passwords."

Can't download any resolution above 720p, but otherwise great.

The best add-on to download video in my view. Thank you.
A couple of think that may improve it even more.
— Download can start with clicking on the file name, not only on Download button.
— The size of the pop-up window (with the list of available files to download) can be twice as wide. Video titles tend to be long. Probably, it can be a setting in options.

very nice

amazing