What was it that the Amersfoort display actually did? Was it a replacement/duplicate empeg front-panel display or did it show alternate data?

From what I gathered, it was an actual video-out plug on the player. The output was the same as what was on the empeg screen, just enlarged to fit an NTSC/PAL video display. It applied a false-color palette to the monochromatic empeg shades (and from what Patrick said, the palette was user-selectable).