From the Github description, a quote: "In a class I taught at Berkeley, I did an experiment where I wrote a simple little program that would let people type either “f” or “d” and would predict which key they were going to push next. It’s actually very easy to write a program that will make the right prediction about 70% of the time. Most people don’t really know how to type randomly. They’ll have too many alternation…
Free will is equivalent to randomness with many (asymptotically infinite) degrees of freedom. Not sure if the experiment tests this. (Pressing a different key or closing the browser tab are also variables in this probability distribution.)
I don't think this is obviously true. I can make a random number generating device with as many degrees of freedom as you like by producing a bunch of vertically polarised photons and measuring their horizontal polarisation. I don't think anyone would describe this system as having "free will".
Conversely humans with "free will" don't usually behave very randomly. They often have reasoning (good or bad) and are able to explain why they took whatever actions they took.
Free will seems to be qualitatively different to randomness.