Forest Whitaker Intros

Whenever he shows up on screen they use the episode like a 'green screen' background and he is superimposed in front... or was he actually there?

I think they used the actual episode as background and added Whitaker in post... and they attempted to match (CGI) shadows of himself and real on set lighting to make it look like he was there.

Any theories... or does anyone know how was he filmed into the episodes?