This was graphically (literally!) displayed yesterday. As I got to Waterloo at the last minute, I had to jump on the second-rearmost coach despite it being very full as the "OFF" light on the platform was already lit. The carriage was absolutely packed, and the fancy display showed the rear five cars as "orange" (full and standing). However, the display showed the front five cars to all be "green" (seats available). Unfortunately the "walk through" feature is not available between the fifth and sixth car of these trains.