The hard drive surface temperatures (Celsius) were measured after the computer had been left on for four hours and also in the same spot for consistency. Only the low and high speed temperatures were measured to see if it was even worth the noise. Room temperature was 15C

Futurelooks posted an interesting article on Hard Drive Cooling. Here's a bit:

Having airflow in the first place is better than nothing, and here the gains appear to be quite substantial even at low speed. At high speed, the noise is not worth it for the extra few degrees. So, if not for the large secret video collection, then for the sake of procrastinating an eventual backing-up of data, DO IT. GET THE FANS. Save the electrons. :)