Thank you to mikeloeven for the idea.
Use this link to get the old youtube format: https://www.reddit.com/r/firefox/comments/74j8r6/how_to_set_old_youtube_layout_permanently_in/

It should work after, make sure to reload.

Plugin is amazing, however I have a plugin called "Enhancer for Youtube" that allows me to play videos in Cinema Mode, and when everything gets darked, the Audio Sync stays on top of the page and it doesn't get darker too.