An extension like Native HLS Playback is required to avoid CORS issues on desktop, install for Chrome | Firefox. Mobile chrome works as a native player itself so it should work fine in mobile.
Why it works? Because making the keys public is never a good idea.
Disclaimer: No content from Sony is hosted on this domain/server, it provides the link to the original host only.
The keys: The keys used in the proof of concept are not saved on this server, rather fetched in the backend and not exposed in the source code which is the ideal implmentation.