I’ve received some feedback about getting a black gif when using GifCam to capture Netflix and other apps & webs, I’m not into movies & shows , but anyway I created a new basic Netflix account to find out the case.
DirectX
at first I thought it’s a technical problem, where the Netflix stream goes into GPU/graphics card instead of RAM , and that’s why it can’t be captured, so I wrote DirectX level capturing code to capture the pixels from the GPU, but that didin’t work, it turned out that Netflix martials is copyrighted with something called DRM (Digital Rights Management).
Virtual Machine
After that I thought to run Netflix inside a virtual machine (I used Microsoft Windows Simulator) and with that the pixels would not be blocked or restricted when capturing from the host, and I was right :)

FireFox

Then I googled the subject more, and found that the browser Firefox has a feature to disable DRM tools, actually the DRM is disabled by default, so you can run Netflix inside Firefox without any capturing restriction, and that is the easier way I guess.
But is it illegal to make gifs from Netflix?
I don’t know, but you must follow the Netflix Terms of Use and the copyright law
Finally
That was a little research I made, and I hope you find it useful :)