Update Sept 29, 2021:
This developer is the best. He successfully works very hard and quickly to keep this addon working while YouTube frequently changes its code.

Original review from 2018:
For 10 months, I have been using the 'Easy YouTube Downloader Express' in Firefox (currently v61.0.2) on the iMac (macOS Sierra 10.12.6) without any problems. The downloaded video is always good quality. There are several great features this addon sports. Unlike KV 'All Video Downloader' you don't have to go to another webpage with the link to download your video. And unlike Video Download Helper, to select your download format you don't have to sort through a long drop-down list of various codec choices, mixed with lots of jpegs and with other media files. In this Web Extension (aka Addon) the choices for download are consistent from one video to the next. It doesn't require thought or promote confusion. It has downloaded videos the other downloader addons could not. I am very pleased.

This is really a useful tool that I ever seared for. It can download the video from youtube with a effortless and user-friently way! Great! Thanks its developers.

Works great, no fuss and updates are quick and effective.

Good! It works easily!

does what it says on the tin

I use a couple of different down-loaders. After around the fifth time my old primary down-loader wouldn't down a video and Easy Youtube Video Downloader Express did it became my primary and the rest are gathering dust. One of the best out there I highly recommend it.

I like this add-on for Downloading Videos, But HD Videos not able to download from it. Thanks

Easy to use, exactly as I needed, which was to download short instructional videos from Youtube so I can view them without internet if needed. For this purpose, I don't need particularly high quality downloads. Creator also keeps add-on up to date.

Es muy fácil de usar y muy útil

I have been using it for some time now. The add-on always worked without problems, is super easy to use and totally unobstructive ( meaning it does not clutter the layout of the page ) no adds. I like it.

It has become harder and harder to find a working YouTube video down-loader but this one works extremely well. There is a choice of download type and size which I find really great, just downloading a sound-file is all that is needed sometimes that saves time and money. It's easy to install and operate and it works! It is worth the little donation to continue using a great service. Cheers

Works very well...excellent add-on that works!

Have used this several times, with great results. Thanks for an excellent add-on!

If all you want is quickly and easy download YT video then this addon is for you. Free version will only download resolutions up to 720p but actually this fine with me. Never had any issues with it, works perfectly fine.

Hats off to the developers. I bought them not one, but two cups of coffee for this amazing add on. Really easy to use. Fast. Automagic. Love it!!

I think it is greatest addon. Thanks always ;)

I can easily download videos to make memes.

I donated many years ago for the PRO version and never regretted it. This add-on works flawlessly and always has, it is the best for downloading from youtube. and the MP3's are real file size and not a bloated 20mb + .. Your the best Dishita. Thank you

Just an excellent video/audio downloader. I've used it for years on an almost daily basis. Any problems I've had have been dealt with speedily by support staff. Makes videos up to 1080p and MP3s up to 256kbps. Easy to use and fairly idiot-proof.