Audio-free videos are often allowed to autoplay (though you may need to flag them as muted as well). TFA'a video autoplay just fine in both Safari and Firefox.

I'd support that (as if anyone's asking me...) on three conditions:

1) Maximum duration of, say, 10 s (with mandatory looping)

2) Maximum display size of, say, 25% viewport area

3) Browsers must enforce "Click to stop" on these "video-img" elements even if there are other DOM elements on top.

I believe that this is the case on Safari, don't know about any other browsers though