Autoplay of MP4 does not work

Daniel - if it is you looking at this - thanks for the help with my earlier audio query, I got it working, but the confusion was that it doesn’t play in the editor, only in browser preview, which I didn’t expect.

I have an MP4 positioned to appear and start at 9s in the timeline. I have set it to autoplay.When I play in the editor timeline it works fine, but it will not start in Safari 11.1, or in Chrome 66. It just shows as a still pic.
Can you help please? I have attached a zip of the hype file.

Video cannot autoplay in the latest desktop browsers unless it is set to be muted or has no audio tracks.