If you watch the handwriting at second 52, the lag is barely noticieable, even on slo-mo. What is happening is that a light grey shadow appears very fast, and

If you watch the handwriting at second 52, the lag is barely noticieable, even on slo-mo. What is happening is that a light grey shadow appears very fast, and then the ink "fills in" fluidly until achieving its final dark grey. The effect is like some "magic ink" that dries in contact with air. It's not exactly like pen and paper, but they've achieved an effect that psychologically works well for me. The Sony epad [1] seems to be right there in terms of writing speed, if we can trust either video. [1] https://www.youtube.com/watch?v=zrp9TxgFBdw https://www.youtube.com/watch?v=zrp9TxgFBdw