If you’ve ever been a kid watching “Sesame Street,” Being Elmo: A Puppeteer’s Journey is pure nostalgia. If you grew up in the era of “The Muppet Show,” The Dark Crystal or Labyrinth, then it’s the most awesome nostalgia.

This is the story of Kevin Clash, the puppeteer who ultimately became in charge of Elmo on “Sesame Street.” As a kid, he cut up his parents’ furs to build his own puppets. He learned from watching behind the scenes footage of Frank Oz. By the time he was 17, he became a local Baltimore celebrity putting on puppet shows.

Clash got jobs on “Captain Kangaroo” and “The Great Space Coaster.” He actually had to turn down The Dark Crystal to stay on the shows, but by the time Labyrinth came around, he was in charge of the fiery that throws his eyeballs in the air, catches them in his mouth and they come back out the sockets.

Along the way you learn tricks of the puppet trade. Ernie’s neck is a coffee can and Clash can feel the ridges when he sticks his hand up. Jim Henson invented an invisible seam made out of fleece that wouldn’t show up on camera.

Once he’s hired for “Sesame Street,” Clash starts demonstrating the subtleties of puppeteering. You have to keep the puppet’s mouth slightly open, so it looks like it’s smiling. Keep it active, looking around, otherwise it looks dead. But don’t overdo it. A subtle bob works better than vigorous shaking. If the puppet has to scratch his head, bring the head down so less of the arm rod shows.

Another rare find is a corporate video Clash made with Henson and Oz. In the early days, Elmo had a rough voice Clash describes as more of a caveman. When he found the high pitched innocent voice, it was magic. Seeing him entertain Make a Wish kids is touching.

This is a basic documentary with behind the scenes footage and talking heads. It’s the subject that’s so interesting. I don’t think kids could sit through the technical depictions and discussions of puppeteering, but maybe they’re inquisitive.

When you finally get a chance to see this yourself, you won’t have the benefit of Elmo himself dancing around over the end credits. During the Sundance screenings, Clash broke out Elmo and performed in front of the screen. I’m surprised they let him bring that property out in public, but just imagine a silhouette of Elmo moving back and forth around the credits list.