Disagree. On the consumer side, I care more about auto-playing audio than bandwidth. On the content owner side, I only want my videos to autoplay (in most circumstances) if it were accompanied by the audio. If I didn't care about audio accompaniment I can already use GIF.
Perhaps the iPhone should autoplay videos, but muted until you hit a speaker icon (or something). Either way, forcing everyone to use GIF is horrible because of how inefficient it is.
I'd like a global option and also some simple per site UI.
This is how the click to play in Firefox works, it's nice. One thing I haven't figured out how to do is trust embeds from a site (for example, Youtube and Vimeo both have well behaved embeds, so I'd like to whitelist them, but not many of the third party sites I see them on).
That's only a UI issue. You don't need compression to be horribly inefficient to achieve that :)
For example <img src=vid.mp4> could autoplay looped video without audio, just like GIF, except using tiny fraction of bandwidth and CPU (thanks to HW acceleration) than GIF.
