Greasy Fork is available in English.
Select a youtube resolution and resize the player.
I know there were some issues with resizing that should now be resolved with an update made today. If that was your issue, please give it a try. If you are having some other issue, can you please explain to me what needs to be working better and I can take a look?
It looks like youtube has broken the script again. It appears they've moved to some godawful tablet-first design. Google are truly at the cutting edge of enshittification