I forgot to turn my video recorder off and accidentally recorded my screen when I watched some series on some website. When I re-watched the video a few weeks later, I noticed that the part where the series was played (on full-screen) was a totally plain black screen. I found it weird so I thought it was a bug or something but I discovered it's not. It was apparently some kind of protection to prevent video pirating and the idea just wow-ed me.

I'm a fresh CS student who's taking a lot of courses in security but I have no idea how does that idea work especially because I could see the video but the video recorder couldn't. Can someone explain how that works?

  • 5
    It likely works because the recording software intentionally checks if the video has DRM and refuses to record it. It's trivial to bypass that using a technique called the analog hole.
    – forest
    Apr 10, 2018 at 8:57
  • 1
    There are many DRM copy protection enable hardware and software around. You can google the video recorder brand and model look for info related to DRM protection. en.wikipedia.org/wiki/Digital_rights_management I mod down the vote because this topic has nothing to do with security, e.g. like preventing keylogger capture your computer screen.
    – mootmoot
    Apr 10, 2018 at 10:54
  • 5
    Why are people voting to close this question? It is a well-written and on-topic question about DRM.
    – forest
    Apr 10, 2018 at 11:06

1 Answer 1


As pointed out by the comments, the reason that this happend is because of my video recorder could recognize that the video being played has digital rights management. For more details on how this technique work, check wikipedia.

  • Are you sure it's that, and not that it's technically impossible for software to tap into this data?
    – Lamp
    Nov 7, 2021 at 6:40

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