This being a Morgan Spurlock movie, it's hard not to wish he'd structured it like Super Size Me, wondering what happens to a person after subsisting for a month exclusively on one insidiously innocuous UK boy band. But Spurlock's One Direction: This Is Us doesn't even put on investigative airs, and seems therefore about as journalistically useful as a promoted tweet. In 3D, it documents multiple mild-mannered hangouts with the pop juggernaut cobbled together by Simon Cowell from individual auditions on The X-Factor, and is a testament to puppet-master Cowell's special (pre sex-scandal) genius: These lads don't seem superfluous to their shared enterprise, even if they all are. On stage in packed arenas, Harry, Liam, Louis, Niall, and Zayn come together electrically, like robot-lions forming Voltron. Offstage, seeming alternately and adorably like regular blokes or a basketful of puppies, they do some reflecting on their good fortune amid much goofing around. Perhaps most illuminating are the amateur mob-psychology experiments, impishly conducting crescendos and decrescendos of girlscream, the basic unit of their cultural currency. Non-fans will consider this a Zzz factor, at least until being rendered defenseless by the sweet, sweet boys and their sweet, sweet tunes.