Video 1 (bottom/background) = Generic stock photo still image of a classroom
Video tracks 2+3 = the "top" layers
Video 2 (Me, facing right) = video filmed in front of green fabric, talking to an imaginary person.
Video 3 (Me, facing left) = video filmed in front of green fabric, responding to an imaginary person.
The layering on this isn't too hard. Both "green screen" clips had the green wiped out completely, which basically gave me a transparent layer over a transparent layer, over a background image.
The hard part was getting my timing right, and pausing long enough for myself to respond to each statement! This part might take a few tries.