Who: Filmmaker David F. Sandberg, of Lights Out, Annabelle: Creation, and Shazam fame.

Why we care: When director Sandberg had his big horror-movie breakout, he’d never had to deal with a test audience before. His short horror film, Lights Out, went viral in the kind of way that is impossible for Hollywood executives to ignore. Veteran horror director James Wan took Sandberg under his wing and gave him his big break by producing a feature-length version of Lights Out, a critical hit that outgrossed its budget by about 3,000%. Considering that his latest release was the DC Comics adaptation Shazam, it’s safe to say the filmmaker knows his way around an audience test screening by now. In a funny new short, he dispels some common misconceptions about them, while conceding some others.

“The Truth About Test Screenings” illuminates why they’re helpful in the first place, the fact that they can help assess whether certain jokes or scares are working by viewing them through fresh and hopefully far-away-from-Hollywood eyes. The video also demonstrates the kind of groupthink that results when 20 people in a room are asked to explain exactly what wasn’t working in a movie and feel like they must contribute something. Sandberg also reveals some insider info, such as the fact that sometimes vastly different versions of a film are tested simultaneously to see which one scores better with audiences—and that someone viewing the worse version might be the one to take to Reddit to reveal that “this test screening sucked ass” or whatever. The fact that the information is delivered in a playful style of animation, generously larded with jokes, makes Sandberg’s statement that much stronger.

Watch the full video below.