Greasy Fork is available in English.
Select a youtube resolution and resize the player.
I will try to fix any compatibility issues, even though Youtube will probably completely remove the old layout very soon. I probably wont be able to work on it until this weekend though.
You are right. Extensions no longer help switch to old layout. Therefore, they are useless now. Left the only way to switch to the old layout. Overwrite useragent to Mozilla/5.0 (compatible; Googlebot/2.1 . But there are also compatibility issues that I described above. Look what you can do with this. Unless of course they block this last method soon. I wouldn't want you wasting your time. Especially on weekend.
Old youtube layout and your script.
Hello adisib.
Today, google has removed from users the ability to switch using "disable_polymer=1" to the old youtube layout. I always used this in conjunction with yours script and it was great. Till today. :( Firefox AMO has an addon that allows you to use the old youtube layout, but it conflicts with yours script (stopped switching to the specified resolution over time) as with similar to your script functionality another addons. So I wanted to ask you. Can you add some code to your script to switch old youtube layout (this will eliminate conflicts) or tweak your code so that it does not conflict with this addon https://addons.mozilla.org/en-US/firefox/addon/restore-fast-theme-of-youtube or this https://addons.mozilla.org/en-US/firefox/addon/youtube-classic ???
PS: Cookie, dom.storage, dom.indexedDB always disabled.
I found out what works best with these addons old your script 2017.12.09. Works fine until you refresh page. After that, ALL the following videos will be in resolution "Auto 360p". Maybe it'll help you where dig. :)