This seems slightly limited in its current form in that they either have choose to either shoot the rendered background as-is (making it harder to modify in pos

This seems slightly limited in its current form in that they either have choose to either shoot the rendered background as-is (making it harder to modify in post production) or specifically turn the areas around the actors into green screens (sort of defeating the purpose). I wonder if they could use some sort of trick like projectors synced with high fps cameras to make the real time rendering invisible to the cameras instead?