I'm constantly impressed by the effort the DPRK is putting into securing their devices.
I've just skimmed it, but:
The talk describes what is really an extreme form of DRM, the tablet can only open media created and signed by the government or media created and self-signed on the tablet.
Users can't exchange files, if they try the signature check fails.
It's very similar to what they presented last year on RedStar OS, but this seems to be taking it to even greater extremes.
In RedStar OS you could transfer files, but they'd get watermarked. In someways that's even scarier, because they can log ever user who touched the file.
Really very interesting, it will be fascinating to see how this progresses (as well as terrifying).