The show that inspired them is actually quite cool (Score 1)

>It all started with a documentary we were watching on TV about some history professors and
>traditional builders heading into the English
countryside to build a couple of trebuchets.
>Their aim was to see which design would have been more practical for use in the 14th century.

The show in question was an episode of the PBS
series "Secret of Lost Empires":

http://www.pbs.org/wgbh/nova/lostempires/trebuch et

The whole series is very interesting -- they try
to recreate an item from history for which some
or all of the underlying technology is totally
lost, except perhaps for fragmentary text
descriptions. The two teams use different
counterweight theories, with interesting results.

I just wish they hadn't flouted historical
accuracy by using as a projectile one of those
big blue things from "Star Wars Episode 1"...