Need help screen recording

For context: There’s an app/software that my teacher asked me to download on my Windows PC to view his recorded lectures. I’ve finished watching the lectures, but I’d like to screen-record some parts for future reference.

However, I’m unable to do so using regular tools like PowerPoint screen recording, the Snipping Tool, or Zoom screen share. Every time I try, the recording just shows a black screen.

What is a sure-shot way to screen-record in cases where the app has strictly restricted recording? I’m a layman and not very tech-savvy, so I’d really appreciate an explanation in simple terms 😅