I am using Moodle 3.5.2.
I think Moodle will play .m4v videos. When I upload the video file, it plays fine.
But, when I create a page, and choose "Insert Video File" (Atto HTML editor), and copy the link from box.com, I get the message: "No video with supported format and MIME type found."
The link from box.com looks like this:
Does Moodle need to see the .m4v extension? Maybe box.com changes m4v to some proprietary format?