[mothered]

Now they want a video with the G-Hub app opened on PC and the non existing keyboard with the S/N.
Just send a corrupted mp4 file?

Correct.

No doubt they'll keep requesting It, so send It In a different file format each time and assure them that It's working perfectly fine on your end. This gives the Impression as though you're doing your utmost best to comply and resolve the matter. There's another manipulation that you can apply to the file, but first see how you go with this. If need be, I'll discuss the other one afterwards.