In test, but seems easy to use and working well.
I use it for regain the OLD Youtube interface and keept my Youtube addons and userscripts working on it.
By example this one:
Youtube - Restore Classic
https://greasyfork.org/fr/scripts/34818-youtube-restore-classic
MORE Infos:
Disable Polymer not working anymore: If the extensions and scripts aren't working for you, try this workaround:
https://www.reddit.com/r/youtube/comments/h9kpbp/disable_polymer_not_working_anymore/fuzp9k4/

Thank you for fixing Youtube.

I use this for reverting YouTube back to classic template by telling YouTube that my browser is Google Bot.

Brillant. Easy to install. Works straight away. Thank you

This one works flawless! Was recommended at privacytools.io that how I found this. Should be on Mozilla Recommended Extensions too.

非常好用的扩展,作为web开发人员经常要用到

有时候就要用到。很依赖了。现在担心Mozilla 扩展推荐计划。这个鬼计划会让作者失去更新的计划

Works pretty well! It would be nice to have a list of websites/domains that overrides have been configured for.

Absolument PARFAIT ! Ne demande aucun redémarrage de Firefox, pour ma part a permis d’accéder à un site qui ne supportait pas Firefox et me demandais chrome. Ravie !!

Doesn't seem to be designed for easy mobile use