Martijn
What happens if two people click simultaneous then? I am hoping they have some sort of error correction there. Not the mention JavaScript timers in the browser don't always take 1 seconds as 1 actual second. (Run a JS based clock long enough and it will start to differ from your computer clock.)
Mark Dain
If you hover over one of the clicks, it sometimes says "Clicks: 2" which happens a lot of numbers like "10s". There's also treyp.github.io/th... if you want more data (especially distribution)