No video in preview in browser Safari 12


I am considering using videos in my website, before implementing video (or moving images) i wanted to try is out and made a square MP4 video.
When using the command Preview in Browser Safari would not give a video.
Chrome is playing the video fine however.

Even after checking Safari prefs which has ‘allow play all content from this website’ it would not play it.
After exporting the project to my desktop the video is playing as expected.

Maybe a little flaw in the code? Or is there anything I can do.


Can you share a link to the website, so I can take a look at what’s the problem here?