When Betsy Walkup entered that dance audition in 2007, she had an edge: She had been taking classes for about a year — and she was younger than most of the people trying out.

“I got into hip-hop when I turned 60,” says the kindergarten teacher from Bronxville. (That’s Betsy, No. 61—for her age—in the center at right, in a photo courtesy Gotta Dance & NBA Entertainment.)

“I discovered that I loved it and that it was genuine, so I took a class every Saturday at New York Sports Club in Manhattan, on Broadway.”

The folks in those Saturday classes called her “Betty,” not Betsy, so that became her hip-hop persona, a character she’d play, a woman who could shake things that the kindergarten teacher would keep still.
Betsy would use an inside voice; Betty was as wild as the street.

Both are about to become larger than life, featured in the new documentary film “Gotta Dance,” by Bedford filmmaker Dori Berinstein. It gets its New York theatrical release on July 31 at the Beekman Theater in Manhattan.

The film opens with a quote from theatrical great Florenz Ziegfeld: “Age doesn’t matter unless you are a cheese.”

It’s the central theme of “Gotta Dance,” a lively, fast-paced film that follows the inaugural season of the New Jersey Nets NETSational Senior Hip-Hop Dance Team, a dozen women and one man who performed at six games in the 2007 season.

Berinstein captures it all — from auditions to selection to rehearsals, rehearsals and more rehearsals — building to that first half-time performance when the NETSational Seniors caused, well, a sensation in front of 20,000 basketball fans.

At an age when some of their friends might be gettting fitted for artificial hips, 13 seniors were out there, center court, doing hip-hop.

Talk about defying gravity.

Berinstein’s cameras continue to roll after that first show, following the team through the wave of media requests  and some hiccups caused by their newfound success.

The cameras are there as three of the women shop at the White Plains Galleria, hoping to find a more Betty  wardrobe for Betsy.

After the audition, Betsy marvels at what Betty has just done.

“I kinda did a pole dance,” she says in amazement

Later, Betty/Betsy (as she comes to be called) is in her classroom at the Denton Avenue Elementary School on Long Island — in a segment titled “The Best Day of My Life” — teaching her kindergartners a rap song with an anti-bullying message.

Berinstein and editor Adam Zucker honed 250 hours of footage into a 90-minute film that has brought film festivalgoers to their feet from Tribeca to Williamstown to Palm Beach, where it won the audience award.

“I had in my mind for a long time a film that would be a celebration of life, of aging, of people taking their dreams and going out there and doing something they always dreamed of doing but never got the chance to do,” Berinstein says.

“Gotta Dance” goes beyond a cute movie about old folks not acting the way society expects them to act.

One of the sweetest scenes comes late in the film, when the Nets youngest dance team — kids in their tweens and teens — shares the floor with the seniors. The connections they make, born of mutual respect, speak to the power of shared experience.

Before a screening in Mamaroneck last night, film critic Marshall Fine said he knew his Emelin Theater Film Club audience would respond to “Gotta Dance.”

“Audiences tend to look upon documentaries as spinach, but this one’s different,” he said. “I won’t say it’s junk food, but it’s not spinach. It’s very entertaining and uplifting. I knew it was right over the plate for my audience.”

The hundred or so film fans at the Emelin screening didn’t disappoint. When the first dance number was shown, they burst into applause.

Walkup says she still gets a thrill performing, something she and a half-dozen of those trailblazers have continued to do with the Nets.

“The surprise is when you go out on the court and they still love us,” she says. “They still think we’re super. They’re laughing and happy as soon as we start doing hip-hop. I sometimes wonder ‘What do they see in us?’

“But sometimes we get more applause than the real dancers,” she adds, referring to the much younger Nets Dancers, two of whom had grandmothers on the original senior hip-hop squad.

Berinstein’s films have won awards, as have the Broadway shows she produced, including “Thoroughly Modern Millie” and “Legally Blonde: The Musical.”

She combined her passion for film and theater in 2006’s documentary “ShowBusiness,” which chronicled a Broadway season through the prism of four shows.

Her theatrical side is evident with the rollout of “Gotta Dance,” which will hit the ground running next week.

“We want to make it an event,” she says enthusiastically.

Next Thursday at 11 a.m., the senior dancers — and all the Nets dance teams, mascots and some stars of Broadway — will gather in Duffy Square near the half-price ticket booth to teach the “Gotta Dance Slide” to anyone who’s game.

Next Friday, “Gotta Dance” opens a one-week run at the Beekman Theater, 1271 Second Ave. (212- 585-4141.) As they did at the Emelin, some of the dancers will perform after the Beekman screenings and there will be talk-backs and giveaways.

The film then opens in three theaters in New Jersey, in Portland, then in Los Angeles and on to Arizona and Florida, two states with their share of seniors who Berinstein hopes will connect with the film.

The documentary, it seems, is just the start of things for “Gotta Dance.”

• Royal Caribbean Cruise Line has a “Gotta Dance” multi-generational hip-hop dance program on 20 of its ships.

• A social-networking Web site — www.gottadancewithus.com — looks to connect those who love to dance but haven’t tried. The film has a presence on YouTube, Twitter, Facebook, MySpace and Flickr.

•  The “Gotta Dance” Project is a non-profit designed to bring generations together through dance, health, fitness, and mentoring. (Donate at www.gottadancethemovie.com.)

• A Broadway adaptation of the documentary is in the works.

• There is talk of adapting the documentary into a fictionalized feature film.

“To me, it’s a lot more than a movie. It’s more of a movement,” Berinstein says. “To inspire everybody to go chase a dream and to not look at things like ‘Oh, now that I’m this age, I can’t do this anymore.’”

“Gotta Dance”
Where: at Beekman Theatre, 1271 Second Ave. (between 66th and 67th streets).
When: Opens July 31. Limited, one-week engagement.
Screenings: Noon; 2:15 p.m.; 4:45 p.m.; 7:15 p.m.; 9:20 p.m.
Call: 212-585-4141

You can win tickets to Gotta Dance. Go to www.gottadancethemovie.com/contestentry.html

Next at Emelin
Next Wednesday at 7:30 p.m., the Emelin Film Club screens “Cold Souls,” with Paul Giamatt playing an actor named Paul Giamatti who finds a company that can extract a person’s soul and deep freeze it for later use. When Giamatti’s soul is stolen, he sets off to find it. Writer and director Sophie Barthes will join Marshall Fine for a post-screening Q&A. For tickets, emelin.org.