Fix Youtube Autoplay is an open-source extension that returns respects your choice of Autoplay.
YouTube now decided to enable Autoplay by default for all new site opens and page navigations. This is an attempt to fix that and remember the choice across page visits.
On page load, it checks the current value inside the page and compares it to the one remembered by the extension. If they are different, it triggers a click on the Autoplay button after 5 seconds.