Comment by thayne

Google has a history of sabatoging Youtube on Firefox. See for example https://www.tomshardware.com/news/youtube-responds-to-delaye....

It isn't unique to youtube either. Gmail offline mode only works on chrome, even though other browsers have the necessary APIs. And menu copy and paste in google docs uses a special chrome-only extension that google pre-installs in chrome, instead of the clipboard API that works in other browsers as well.