I want to disable this very annoying youtube autoplay feature on my web browser. I try to disable it using youtube UI but after some time it turns on and autoplay starts working again! I am using Firefox 70 on Ubuntu. The answer from 2015 on this site doesn't seem to work for me.
I'm with you, I can't stand this feature. I don't log in to Youtube and I browse in private mode so autoplay is enabled every time I close the browser.
I wrote a userscript that checks if autoplay is enabled every 10 seconds, and disables it if so:
The usual applies: no warranty, have only tested it on Firefox with TamperMonkey (Works On My Machine™), etc.
Though if it doesn't work for you, you can open an issue on OpenUserJS and I might have time to look into it.
This seems to require an extension now. The current UI for YouTube has the auto-play toggle built into to player. It is always on by default each time you go to the site after having left. After several tries I found "Disable YouTube Auto Play" which still works and doesn't try to do anything else. I am not linking because google may very well break things again in the future.