Previewing a video file

I’m using the layout field and I have a customised fieldset that will show a video.
This video url comes from a CDN as an .mp4 file rather than from Vimeo or Youtube.

I want to show the video (or a thumb) for the fieldset preview but I can only make it work if embedding a Vimeo link, for example.

I understand that this is not an issue, or something that people might encounter so often – but I was wondering if there’s a way to show something in the preview of the field other that ‘Insert a video URL’; which doesn’t disappear after inserting the url.

Thanks a lot

The way forward would be a custom video preview with an HTML video tag, similar to this audio block example, but without the hassle of fetching the data because you have a URL: