I will try to share with you my uncertainity calculations
a) on the video we can see that the roomba has the "extra much dirt" feature on, which makes him circle and therefore loose much time.
b) from the previously posted video on the forum about the roomba contest, we can see that the roomba achieves 63% of cleaniness.
this is a single shot measure, no stats.
there were obstacles
the arena size was larger
the given time was 7 minutes not 2.5
c) there will be an error of measure by the clever, but not perfect podcast guy's, let say +-1%
d) all the previous posts in ths thread
I suggest to repeat the cleaning measure as many times as there are posts. most of us will win once then. As there are not that many books to win, an average will be ok