I have been using this add-on for some time. Worked great.
Then I encountered:
cannot detect url_encoded_fmt_stream_map or adaptive_fmts
Tried to search for solution. Couldcn't find any.
Tried to reinstal the add-on.
That solved the problem :)

The best add-on to download from youtube. Thank you.

One button click to quickly download a video. Worked totally as expected.

Good

works well on android!

One of the few yt downloading extensions that actually work as of right now. Really nice UI for selecting format as well.

Удобно и просто )

sehr zufrieden

This addon works perfectly. To have it auto-convert videos to MP3, go to addon options, install native client and install FFMPEG and select Postprocessing -> Convert to MP3. Voila!

good

From my own experience, this IS the best YouTube video downloader, so far, there are no other competitors. It is simple, functional and practical. From download to conversion every feature runs perfectly. Lately there was an issue with some downloads (my assumption, that it might have been due to the owners of Youtube), but soon enough an update was provided and fixed it, demonstrating the care, affection, and professionalism users get from the developer. Simply, I recommend this add-on as a MUST, above all other video downloaders.