Marshmallow Man

In the "Marshmallow Man" demo, I believe that the reason for his expansion is the fact that there was no pressure in the vacuum. Because of the fact that there was no air in the vacuum, the man lost his shape and expanded due to the lack of pressure. When the vacuum was opened, air and pressure reentered the vacuum. The man had just been free to expand, but all of a sudden pressure was keeping him together. This is why he collapsed and was crushed once the air was let into the vacuum.