You
You start watching this wondering what the fuss is about. Stupid computer scientists, you think, wasting our time with unremarkable things. Then you realise they've really buried the lede. Because at 1.31 you are, like, woah!
Suddenly they stop showing him the ball, just a visual cue predicting where the ball's going to be and his hand moves straight there. Uncannily. Robotically. It makes you see 'catching' completely differently. It's not a gradually adaptive coming together, all course-correction and curves, it's suddenly angles and fixed points. Inhuman. Inorganic. Brilliant. Suddenly you get a glimpse of a future AR goalkeeper. And you think about dartboards: