MP4 360p und MP4 720p:
Button text "pls. wait, this can take time..."
Download attempts lead to a file with size 0.

MP4 1080p (Full-HD):
Works, but sometimes with and sometimes without youtube file names.

On the so called support page it says:
"UPDATE 01-JULY-2019 : A fix v 15.3 for downloads stuck at "Pls. Wait" message is now fixed and pending mozilla's review and approval, this is expected to take upto 48 hours. You can check for latest v 15.3 here - https://addons.mozilla.org/en-US/addon/easy-youtube-video-download/ ".
The update is still not available today (11-July-2019).

This doesn't work anymore. Support page says download version 15.5 , but this version is not available here. The latest version is 14.4, from 3 months ago, while the support page states a new version was released on July 1st.

-- Edit: It works again!

-- Edit: Works!

easy to use... thanks

Correction of former statement: Since the last update it often is useful for downloading in 720p, if an higher resolution is available, that then can only be downloaded by plus-version. For many videos this is enough for me, especially, as there seem to be missing an alternative, since youtube changed its architecture. Sometimes only lower qualities can be downloaded.

good

best so far

Finally, a YouTube download plug in that claims to allow 1080p downloads, AND delivers what's promised. Even better, if you have any problems, the developer responds to emails very quickly (responded to mine in less than 3 hours), and works with you to resolve the problem as quickly as possible.

nichts zum downloaden von Videos vorhanden.

This is what I'm getting when simply trying to dl mp3 128Kb from YT. I call BS. They just want money, straight from the start.
"Youtube switched to separate audio/video streaming technology for higher quality formats and no longer provides direct 720p (Since 24 September 2018)/1080p/mp3 streams. Converting these streams to downloadable formats for you needs powerful server infrastructure, therefore 1080p/mp3 downloading has been limited to PRO users. Read more at - https://videodroid.org/pro_upgrade.html. FREE users can download all formats in CACHE where some PRO users fetched the video/audio in past 24 hours, to test the feature you can try downloading popular videos."

Seems to be working again. Thanks! Those of you who can, please donate to his cause.