Windows 10N reinstalled but can no longer play videos?

I recently reformatted my hard drive and reinstalled Windows. Since then I can no longer watch videos on e.g. Netflix and always get an error. Same with other streaming services too. I ask for help:/

What mistake, then could you possibly help?

It seems to be due to the browser. I use the Opera Browser as before. The error code is 07355: / Google chrome works

It could be due to the ffmpeg extension.
Download here:

https://github.com/...t/releases

and Win10N has no media player, to use this function you have to download and install it:
Media Feature Pack for Windows 10 N (May 2020)
Download here:
https://support.microsoft.com/...3c9f6a4439

that's what I was able to research - without being able to verify.