http://www.humansinvent.com/#!/11211/the-film-that-reacts-to-your-emotions/

Humans Invent spoke to the film’s director, Alexis Kirke, to find out how it all works. Kirke explains that sensors are used to gauge the emotional state of the audience. He says, “We’ve imported four sensors from the USA, we’ve got a heart rate monitor, an EEG monitor (brainwaves), a perspiration monitor and a muscle tension monitor.”