how to make SSL compatible with safari video play please

Hello,

I met headache issue with video play only in Safari after SSL setup. Videos play well both in SSL or non-SSL status in Chrome and firefox. I supposed the reason seems related to incorrect intermediate certificates setup, as per at technical topic https://stackoverflow.com/questions/4660189/cannot-view-quicktime-movies-over-https-in-safari-or-uiwebview

so, I asked an technical to setup new wildcard SSL for our multisite(Payable work for wildcard SSL deploy), and created a fresh site with no plugin activated, you may find SSL work well:
https://www.sslshopper.com/ssl-checker.html#hostname=https://videotest.lovcour.com

Here is my test process:

by default, the site was created https://videotest.lovcour.com/ 1(not https), https://prntscr.com/jdygmc
2.I check the root site, it is still https://lovcour.com, but not https://lovcour.com, I just support it is saved in database but I can not change it.

3.if access the subsite: both https or http is accessible ://videotest.lovcour.com

4.Upload a standard mp4 video sample downloaded from a professional development site which guarantee the video is support in all of browser,

the default url of the uploaded video is https://videotest.lovcour.com/mp4_video/ 1, it is not https, please check the screenshot: https://prntscr.com/jdyj3z, and the video is play both frontend and backend, and Here is frontend screenshot: https://prntscr.com/jdyj9u
6.Here is screenshot: https://prntscr.com/jdyjtt, which show I changed the site url from https://videotest.lovcour.com/ 1 to https://videotest.lovcour.com/.

The video URL will automatically change from http to https, here is screenshot: https://prntscr.com/jdykag

As you see, the video will not play both at backend and frontend, and just show the error as:

Media error: Format(s) not supported or source(s) not foundmejs.download-file: https://videotest.lovcour.com/wp-content/uploads/sites/59/2018/05/mp4_video.mp4?_=1
I would like to have your professional suggestion on SSL compatible setting for Safari, how to resolve it please?

Thanks so much.