Udemy videos not displaying with Safari 14.0.3

I have a problem with the vides from the Udemy training site since a recent update to Safari. I'm using it on a MacBook Pro with Mojave installed(I need this version of the OS to keep my music software and related plug-ins working).

The rest of the webpage is working. The problem is that with the Udemy training site all of the videos are shown with a black screen. I've tried turning off extensions, opening the site in a private window, reloading the page, restarting the computer and removing Udemy site cookies but none of those steps helped.

Has anyone else seen this issue or fixed it before?