“Playback” starts interestingly enough. A young man named Harlan Diehl walks around a country farmhouse with a video camera, filming recently slaughtered bodies (as we learn later, it’s Diehl’s adopted family being filmed and he’s the one who did the slaughtering). His camera then focuses on a little baby left untouched in the mayhem. Before we learn the reason for his murdering spree, however, he is gunned down by police officers. Would it surprise you to know that the baby survives?