What is on the bonus disc in the Trilogy DVD set?

There is a DVD box set in the U.S. called Ghost School Trilogy, from Tartan Asia Extreme.

It includes Whispering Corridors, Memento Mori, and Wishing Stairs, as well as a bonus disc. I was curious to see what was on the bonus disc. I already have Whispering Corridors and Memento Mori, but I could trade them in and look for the box set if I needed to.