There’s no reason for sane individuals to make documentaries. First they have to find someone doing something interesting, then they have to film them for months, even years, hoping that something dramatic will happen, and finally they’ve got to take hundreds of hours of footage and give it a beginning, a middle, and an end. The director of “Confessions of a Superhero,” Matthew Ogens, has pulled off 2/3 of the job, but that missing 1/3 consigns this documentary to the status of a video sketchbook, full of personalities and color but signifying nothing. What’s the most depressing job in Hollywood? Being one of the costumed characters who prowl the sidewalks outside Mann’s Chinese Theatre in Hollywood, posing for snapshots with tourists. But “Confessions of a Superhero” has managed to find four of these caped panhandlers who, miraculously, haven’t become totally jaded.

Each of them impersonates a superhero: Christopher Dennis claims to be the secret lovechild of actress Sandy Dennis and is obsessed with Superman; Maxwell Allen has anger management issues and dresses as Batman; Joe McQueen is a formerly homeless black actor who becomes the Incredible Hulk, and Jennifer Gerht is a former prom queen from Tennessee who impersonates Wonder Woman.

Mr. Ogens obviously spent months filming these four as they go on auditions (they all cling to fading dreams of stardom), struggle with relationships, and lie about their pasts. But nothing elevates the material beyond the video diary of some struggling actors. The filmmakers occasionally exhibit outright desperation (Batman visits a psychiatrist in costume), and though the music and cinematography are terrific, at the end of the day these superheroes are defeated by the mightiest supervillain of them all: so much time, so much footage, and nothing happens.