Safari uses some sort of algorithm to determine whether you actually want the autoplay to happen. For example I've noticed that if you play a video on a websit

Safari uses some sort of algorithm to determine whether you actually want the autoplay to happen. For example I've noticed that if you play a video on a website during that session, it will allow autoplay from scripts on that page (not 3rd party) for the rest of that session. Same for unmuting an autoplaying video. This is all undocumented though and through personal observations, as Apple seemed to stop posting Safari documentation years ago.