It's basically only on the IFE screens (so, not the frames with the Y screens which are flat silver, but ones with a notch on the bottom and definitely not the one with the black screens or the even older grey ones) you can see in the EK website promotional material, so I imagine only the frames with PE (that kind of delivery time onward).

That said, I think I recall seeing an option on the silver screen IFE equipment earlier this year but didn't see it recently, so maybe it is something that the hardware can do, but they've turned it off...