Hi there,
I checked the case with Windows and it worked correctly but I compare it with my Macbook Pro and it takes longer to load so many times that might cause the issue and make the visitor believe it is not working.
I checked the video in details and actually extracted the actual file and checked, it is about 10MB which is pretty decent and actually perfect size for a video.
I am not sure why sometimes it is not loading fast as it should in Windows. I suggest that you also check for the Codec settings as sometimes devil is in details. Here I found a good information regarding the codec support of browsers which you can check in your video editing software:
And also try to add all alternative video formats there.
Thank you.