I noticed that netflix employs a method of preventing users from recording or even taking still screenshot images of the video playback in their browser-based app.
If you are watching a video on netflix (in my case Windows 10 and Chrome) the video will turn to a black screen if you begin to record or screenshot.
What technology is at play here. Is there a windows/chrome API for telling content on the screen to hide if an attempted screenshotting is detected?
Is it possible for a web developer to add this feature to their products?
Most streaming media services now make use of EME https://en.wikipedia.org/wiki/Encrypted_Media_Extensions. The media players built by these services make use of EME to invoke the underlying DRM (Digital Rights Management)
WebBrowser -> HTML5/Javascript -> EME -> DRM
And yes, of course you can build your own solution using EME.