A month later, Krupnick and Marsen were on the early-morning Staten Island Ferry, along with two other dancers and Krupnick’s wife, carrying boomboxes and cameras and ducking security guards, shooting guerrilla-style test footage for “Girl Walk//All Day,” which Krupnick describes as “an epic, 71-minute-long dance-music video” in which Marsen will dance her way through the entire Girl Talk album and up the island of Manhattan. By the end of the day’s shoot, they had eight solid minutes, which Krupnick cut together and tossed up on Vimeo as a kind of trailer for the full movie, to see if anyone noticed. The first day, 11 people watched. On Day 2, six did. Then on Jan. 12, Gothamist posted the video, and an hour later it appeared on The Huffington Post home page. By day’s end, more than 17,000 people had seen it. On Jan. 28, Krupnick put up a donation page on Kickstarter, hoping to raise $4,800 from strangers to help him and his collaborators make and distribute the complete video. They gave themselves 45 days to meet their financing goal. It took six. By Valentine’s Day, they raised $12,000, and the trailer had been seen almost 60,000 times.

It is no surprise that people go nuts for the trailer. It is weird and joyous, popping with youth and energy. At first, Marsen looks more like an enthusiastic and slightly dorky amateur than a trained dance pro. She wears regular tennis shoes and worn gray cords and an oversize, multicolored jacket, and at one point she falls off the railing of an escalator. It’s not until a minute or so in, as she twirls and gyrates through the ferry’s upper level, staring down the camera with a sly smile on her face as sleepy commuters pretend not to notice, that you start to suspect that you’re watching something more than a little magical.

For the past six weeks, while Marsen’s Internet celebrity grew, her physical self was in Mumbai, where she is staying with strangers she meets through CouchSurfing.org and taking a monthlong intensive dance class. (She plans to incorporate some Bollywood moves into the full “Girl Walk” video, which she and Krupnick will shoot in April.) We spoke last month by Skype as she sipped chai tea, sitting with her laptop on the floor of a dance studio. “Growing up, I thought that in order to be a successful dancer, you needed to be on Broadway or you needed to be in music videos, doing other people’s work,” she said. “So this is like a dream, to be able to just do my own thing to Girl Talk.” It was often scary during the last few years, she said, charting an iconoclastic path through the New York dance world, where people sometimes get “weirded out” by her ideas and her hybrid style. But she always had faith, she said, that if she kept doing what she loved, good things would happen. “I just didn’t know specifically how to get there,” she said with a laugh. “But now it’s coming to me.”