Its working flawless! Many thanks to the developer!

Subject.org

Need this extension badly for firefox fenix as on youtube mobile site videos in landscape mode are cut out/cropped/zoomed and works correctly when setting user agent to android 7 and below, means youtube loads differently on android 8 and above causing this issue. Hope you can bring it to fenix.

Work fine!
I use it to regain OLD YouTube layouit and keep my userscripts / Addons working on it.

Wonderful

Youtube 'old layout' army incoming ;-)

Отличная, простая вещь. Главное - работает.

Helps me to get the upgraded experiences that devs allow only on a specific device, thanks!

Looks perfect after installation (A LOT OF BROWSERS and versions to choose)! Lets see how it will works in future.