The following website: http://www.themedept.com/demo/getleads/agency.html
Shows a looping video: http://www.themedept.com/demo/getleads/images/video/video.mp4
Wh
I have the same issue (Chrome 54.0.2840.99 m) but I found that it at least works in an incognito session.
It seems that Chrome Dev Tools is not respecting the "Disable cache" setting for videos.