VIDEO: The Stars of Once Sing, Talk Falling in Love in Music Doc The Swell Season

If you saw the beautiful Oscar-winning 2007 musical romance Once, you probably know that in real life, actor-musicians Glen Hansard and Markéta Irglová formed the folk duo The Swell Season -- and fell in love off-screen. Though they're no longer dating, Hansard and Irglová's relationship is inextricably intertwined with the Swell Season/Once story, which is the subject of the music documentary The Swell Season which debuts tonight at Tribeca.

The two performers are unmistakably good together, at least musically speaking; offstage strain is evident in the trailer for the film, which will be a must-see for fans of the duo.

From the Tribeca Film Festival:

After starring in the indie hit Once in 2007 and winning the Academy Award® for best original song ("Falling Slowly"), folk rock musicians Glen Hansard and Marketa Irglova won over audiences and skyrocketed to fame. For them life seemed to imitate art--the onscreen relationship was closely intertwined in both fact and fiction. But when they got back to post-Oscar® reality, Hansard, 35, and Irglova, only 18 years old, decided to dive in and ride the wave of newfound popularity by heading on tour.

This subtle and mesmerizing black-and-white music documentary bears witness to the band and the couple, from musical numbers that pleasure the ears and vibrate the screen to quiet moments where body language and silent pauses linger with foreboding heartbreak. It has always been apparent that the modest duo has a special connection musically, but when the offstage relationship doesn't run as smoothly, it raises real questions about the future. Newcomer directors Nick August-Perna, Chris Dapkins, and Carlo Mirabella-Davis weave an intelligent and poignant tale with universal themes of love and expectations faithfully imbued with the magic and honesty of Hansard and Irglova's music.

Additionally, New York Magazine has an exclusive clip here, which is worth a watch for a peek at the Swell Season in the studio and an intimate moment in which Irglová recalls how she fell in love with Hansard as they grew close through music.

Keep an eye out for an eventual distribution deal, as Swell Season fans are already clamoring for their chance to see the film.