Firefox turns out to need some degree of 'autoplay' support
When I wrote some notes about Firefox's current media autoplay settings, I said, about the central function in Firefox that decides whether or not media can autoplay:
Since I don't want videos to ever autoplay, [...] I may someday try making the entire function just immediately return false.
I did this experiment and I can now report that the result is a
failure. Completely disabling
ie making it always return
false, results in a Firefox that won't
play video at all. It won't play YouTube videos, which doesn't entirely
surprise me, but it also won't even play directly loaded
The videos load, but clicking on the appropriate 'play' button or
control does nothing and the video never starts going.
The situation with bare
.mp4 files surprises me a little bit,
Firefox is presumably putting up the player controls itself, so it
can know for sure whether or not you clicked on the 'play' button.
Based on some quick spelunking in the Firefox source code, it appears
that calls the media's
.play() method. This is the same fundamental
that surprising that it goes through the same autoplay checks; they
appear to be implemented directly in the
.play() handling code
and apply to anything that calls it, regardless of where from or
This leaves me less surprised about the name and behavior of the
media.autoplay.enabled preference and the other stuff involved
here. Given that Firefox needs there to be some 'autoplay', clearly
it could never be the case that setting
false disabled everything here, because then video (and probably
audio) would never play. That's clearly not what people want.