Ui option to set the default AutoplayPolicy permission behavior / fully disable autoplay, and autoplay blocked indicator prompt
Epiphany defaults to enabling HTML5 video autoplay "without sound" to avoid the plague of CNN-style news sites autoplaying talking head videos, but this is not necessarily sufficient. Some users like me want to fully disable any kind of autoplay, and require the user to interact with the video to manually start playback.
Firefox has this setting, and allows easily overriding per-site (ex: for videoconferencing sites) by hinting about the missing permissions for a given site, with this interactive "blocked autoplay" icon widget next to the padlock icon in the addressbar:
AFAIK WebKitGTK/Epiphany already supports the various AutoplayPolicy states, but just doesn't offer a UI to configure it globally, instead of defaulting to "allow silent autoplay" and requiring the user to opt-out on each and every site.