Scientific Tuesdays: Turn Styrofoam into pseudo-plastic

The demonstration of dissolving Styrofoam into acetone is one that we do in the summer ASM workshops, typically selling the demonstration by counting how many Styrofoam peanuts you can crush into a film canister, having hidden a small amount of acetone in the canister before the beginning of the demonstration.

At the end of the demonstration, however, we always end up with an amount of goopy, dissolved Styrofoam mess. The presenter in this video uses the term pseudo-plastic for what is left at the end when the goopy mess hardens. I'm a little curious as to why the pseudo comes into play, but that may have to do with my lack of understanding of exactly what plastic means.

Anybody want to clarify for me?