Most musicians, before a performance, run a soundcheck, prepare for the crowd, maybe pick out an outfit that fits their image — then step onto the stage. Before his, Saul Williams strapped on a helmet, a headlight and boots, then crawled into the Paris catacombs.

He was singing for Take Away Shows, produced by the French Web site Blogotheque, which has filmed pop-up public concerts in odd locations for five years and has spawned hundreds of similar sites. Most of the underground performances are not so literally underground, taking place, say, in cathedrals at night, in furniture warehouses or on hillsides overlooking the ocean.

The trend seems to riff on the concept of underground dinners — one-off, occasionally outside-the-law meals presented in unusual locations that have become something of a foodie benchmark. The dinners are heavily photographed and touted, though they remain elusive to many. Looking at the pictures can feel like you’re gazing hungrily through a window at the odd dining experience but are never invited in to share the food.

Replacing food with music, Take Away Shows open the doors to outsiders. Rather than making music only for those few lucky enough to be strolling by or brave enough to crawl into catacombs, the exquisite filmmaking captures the pop-up concerts and lets the world take a free front-row seat online.

In one video, shot at the foot of the Eiffel Tower, the band Phoenix strikes up its song “1901.” French filmmaker Vincent Moon, Blogotheque’s first director (the site now has seven on two continents), circles the band with his camera. In the background, a bride grips her new husband’s arm. He bobs his head. She slowly breaks into a small grin. On the next circle of the camera, she’s smiling so wide, you can see the gap between her front teeth.

Blogotheque founder Christophe Abric, who goes by the name Chryde, said those moments make the films. “We film how people listen to music,” he says. “There are so many reactions to the music. Kids dancing, a wedding, an old person yelling at us. The artist reacting to this reaction.”

These films have made other young music lovers realize that “you can think about the world as a place to have a concert,” said Dan Knobler, a co-founder of Mason Jar Music. He and his friend Jon Seale, both recent graduates of New York University, took Blogotheque’s example and reinterpreted it for classical ensembles.

Their group, which has filmed six videos, tweaked Blogotheque’s style by reimagining pop songs as orchestral pieces. They hunt down usually abandoned locations in New York to film singers backed by an orchestra.

Trained in music production, Knobler and Seale know how much a room affects a sound. Not only does the orchestral accompaniment change the style of the songs, but each location creates “a whole different way of hearing the music,” Knobler said. Their latest film of Abigail Washburn trails the banjo player through a gorgeous old building, her voice altering as it bounces off the weathered walls.

Other groups, such as Yours Truly and In the Open, both from San Francisco, create similar, quick-take videos.

It’s not just the performance that’s the appeal; it’s the sense that real life can invade at any time. While filming the band Local Natives on a railroad track in Chicago, Yours Truly witnessed a girl being mugged. The music trails off as a few band members run after the thief — and catch him. After congratulations are shared, the band picks up the song again.

The viewer is there in the moment, experiencing the one-time wonder of it all — with the added benefit of getting to press play and experience it again.