it didnt work for me,
hope to fix at the next updates

Doesn't offer 1080p separate video/audio downloads which decent players can work with fine. Instead, requires a premium account to "convert" them.

Since it wants money....

Videos can not be saved in their nativ Resolution, if the Resolution ist different from 144, 360, 720 or 1080. For example: 480p-Videos can only be saved in 360p format.
Videos lassen sich nicht in ihrer nativen Auflösung speichern, wenn diese nicht 144, 360, 720 oder 1080 ist. Bspw. lassen sich 480p-Videos nur im Format 360p speichern.

*Yet another* downloader by programmers too clueless to realise the converter for videos I want to download can run on my powerful PC instead of their servers they have to pay for. m( Or, maybe they're too savvy; maybe they make a nice profit from charging for the use of their servers. I miss the genuine free software of the '00s. If it exists any more, it's impossible to find amist all this GREEDSPAM! ;.; At any rate, it's not evil; the description clearly states payment is required, so it gets 2 stars. (I have tried a worse downloader today.)

Might work, but requires you to buy a pro version to download any videos.

360P only

В связи с политикой Youtube это расширение потеряло всякий смысл для free use: для сохранения в режиме 360р/128KB/s достаточно хорошо себя зарекомендовавшего и более универсального Ant Video Downloader.

Downloads videos yes, but it's also very intrusive. It invades the graphical interface of Youtube with not only the button, but also a big message about a premium product when I tried to download an MP3. I could not remove the message until I uninstalled this. Bad decision on your part.

The very intrusive message is:
PRO UPGRADE : Since Youtube no longer provides direct download links for 1080p and MP3 qualities these two qualities require server infrastructure for processing, therefore user needs to Pay and Upgrade here >>>, you have the choice to pay whatever you want for this one-time upgrade which helps me keep this service alive for all users.

It puts their logo throughout the video which sucks big time. Otherwise was quick and trouble free.

The ONLY add-on I've found that downloads HD videos. Works great on nearly everything, though I've run into one or two videos that it couldn't download.

Update 7/23/20: Software has been updated to change the way it activates for the pro version. Only people who bought in the last 12 months get to keep using it. I paid for pro 15 months ago so would need to pay again but I will not. Dropping my rating considerably for this.