Settings => Search for "Autoplay" => Click "Settings..." => For "Default for all websites" select "Block Audio and Video".

▲ Semaphor an hour ago | parent [-]

Thank you, I could have sworn I had that active, but for some reason it was "audio only".

	▲	styanax 39 minutes ago \| parent [-]
		The about:config settings which you can look up: `media.autoplay.blocking_policy media.autoplay.default` I have mine set to 2 and 5 respectively.