"This is Not a Play" by Somewhat Theatre (Cambridge, The United Kingdom) (20:30 - 21:15)
 
What makes a play a play? What is the difference between a play and an improv set? What do you call a fish with no eyes? A very serious, not at all silly exploration of the nature of theatre and other grand-minded ideas. Somewhat Theatre ask the audience what makes a play a play, then play that play. Playfully.