.MP4 Video Not Playing In SharePoint Site On Mobile Devices

Hi.

I have a video in .MP4 format that plays when sent as an attachment in an email on mobile devices.  

I have also uploaded the .mp4 file to a SharePoint site.  When I navigate to that SharePoint site on a mobile device and click the .mp4 file the video does not play.

What does SharePoint do to cause the video to be unplayable when viewed on mobile devices?