Embedded videos no longer work

Is this a WP 4.9 / Enfold bug? A bit of a concern if it is as it’s not really something special.
I have a small mp4 video hosted on my website which I link to in a video media element contained in a half-width section.
I just noticed recently that it doesn’t load and shows a kind of timer.
This non-working view is consistent across FF, Chrome, IE.
About half way down the home page, on the right of the “Fast charging – up to 11kW” section.

The video itself is fine. If I take the URL of it, it plays fine in any browser. It just seems the embedding / Enfold usage has broken it.

Link to video: https://www.xavelec.co.uk/wp-content/uploads/charge16-3.mp4

Any ideas?