Many videos do not work

I’ve put my current course as the problematic one but it’s possibly not limited to that one.
Also - there are a lot of other similar topics here, but none of the solutions worked.

A video is apparently being loaded, spinner appears but no matter how long I wait nothing happens. I cannot go to its URL, cannot download it (for some reason right-clicking does not allow me to do it, I see such options but I cannot pick them). I work in Chrome but Edge has the same issue. Cleaning cookies or rebooting changes nothing.
Bonus: this video worked fine for me today but now it stopped working and behaves like other videos from this course.
Please help.

Hi @szefu

Did you set up DNS configurations or are you currently using a VPN?

I just tested this course, and did not find any issues with the video playback at this time.

I am using VPN but when I switch it off there is no improvement. Also when I was on VPN other videos were playing just fine.
I did nothing with DNS config.

Also tried on a different computer, no VPN there.
This video cannot be run at all, tried just now.

I just tested the material at the link you provided.

It works fine for me.

Perhaps this is an issue with your internet provider (for example, content blocking or throttling).