Your web-server returns only 2 headers: date and content-type. It may be enough for Chrome/FF but may be a problem for Safari. I found a similar discussion on StackOverflow where they agreed that the Range header is required by Safari to play video content: html - <video> plays in other browsers, but not Safari - Stack Overflow
You can also try to upload the scene to our cloud hosting, confirm that it works on your devices and compare returned headers (maybe content-length is required too?).