Meh, I am not that impressed by the reflexes. I counted the number of video frames in the youtube video (https://youtu.be/WltjaxiowW4?si=KkVJPy_e7ALQulE-) and each square stays lit up for 8 frames, or 270 ms. This is quite long. If you memorize the particular pseudo-random sequence (as Michael did), it's pretty easy to hit a given square reliably.

The key insight and most difficult trick is not having fast reflexes, but actually discovering the pseudo-random sequence is not completely random, and memorizing it.