Why can't I play this .mp4 with a browser on a fresh Windows 10 installation?

when trying to play this video in a browser, it only offers me to download it. On this site, the video is embedded, and the browsers say No Video with Supported Format and MIME type found.

I already installed a Windows media feature pack, which did not work.

It only happens on a fresh Win 10 install. On all other devices, it works.

How can this be and how an I fix this?

Thank you