Out of determination I succeeded, even though by my calculations doing nothing for two minutes cost me $1.60 that I could have made writing code. Of course, I stopped the clock anyway when I clicked on the HN popup notification.
Edit: Just looked at the code. The programmer missed a great chance to gather some data. I would have tracked the fail events using Google Analytics so I could see how many fails on average per user from different traffic sources:
Average time on site won't be accurate in your case because GA calculates it by subtracting time duration between two successive visits. In your case, it will usually be just single pageview so average time will be misleading.
May I suggest using getclicky.com which calculates time based on actual time spent.
Great! One more thought I had: also track whether the failure was due to the mouse or keyboard. When you have gathered a decent number of results I will be very interested to see a blog post with some nice graphs.
Edit: Just looked at the code. The programmer missed a great chance to gather some data. I would have tracked the fail events using Google Analytics so I could see how many fails on average per user from different traffic sources: