Looks like the world has missed one helluva concert. Whatever cynicism one might harbor about the Hail Mary piece of cinema This Is It -- which can be called the first concert rehearsal movie ever -- what this strange yet strangely beguiling film does is capture one of pop culture's great entertainers in the feverish grips of pure creativity.

The screen is filed with performers, musicians, choreographers, crew members and craftsmen, but the movie's laserlike focus is on Jackson. You understand what it takes to attain such dizzying heights in entertainment -- and perhaps why he chose to stay away for a decade.

After its 17 simultaneous premieres Tuesday, the film will open on more than 3,400 domestic screens along with 96 in Imax theaters and another 27 internationally for a two-week run. That run will be extended if demand is there. Demand will be there. (The Columbia release took in $2.2 million from Tuesday night screenings in North America.)

In case someone just dropped in from Mars, This Is It was to be 50-year-old Michael Jackson's final comeback, a planned run of 50 sold-out concerts that were to take place at London's O2 Arena over the summer -- all of which came to a sudden and tragic end with the performer's death on June 25.

Kenny Ortega, the director of the stage show, has put together this movie from 120 hours of digital video footage -- for which Sony reportedly paid $60 million -- taken during rehearsals at the Staples Center in Los Angeles between March and June of this year, along with casting sessions at the Nokia Theater and video sequences filmed on the Sony lot.

What strikes you is how thoroughly professional, even slick, this footage is. Whatever was it intended for -- a making-of doc to accompany the concert DVD, or a television show? This is no footage rounded up from the crew's cell phones. Interviews with the cast, musicians and production personnel further underscore a clear intent to go public with this material.

Whatever the case, how fascinating it is to watch a huge, complicated concert take shape. Make no mistake, this was a show intended for a stadium with a dazzling, mixed-media staging. One can even imagine a music critic in London fuming about overproduced numbers that don't trust Jackson's great song catalog to deliver the goods.

On the other hand, this production may have been just right in scale for the O2 Arena. Dancers pop up through trap doors in elevators operating at toaster speed. A bulldozer rumbles onstage for a green number about saving rain forests.

Shooting in front of a Sony green screen, 11 male dancers are transformed into 11 million. Jackson gets mixed into old, black-and-white movie footage so he can admire Rita Hayworth's wiggle in front of an orchestra and dance around bullets shot by Edward G. Robinson and Humphrey Bogart.

Split screens convey Jackson, nearly always in sunglasses, performing the same number on different days with different wardrobes and different approaches. There's no question who the director is here. Jackson is in complete control. Ortega watches over the production while Jackson manages every moment onstage. His directions are almost poetic. About the tempo of one number, he instructs, It's like you're dragging yourself out of bed. Another time, he says, It has to simmer.

The audience at the Nokia premiere didn't seem to know how to react to rehearsal footage. They giggled nervously at missed cues and interruptions. To be clear: No one should expect a concert film. Jackson clearly is conserving his energy, holding back on dance moves and vocal intensity. He is searching for his concert, the way a sculpture chisels away at marble to discover a statue.

Interestingly, two of his best songs, Billie Jean and Man in the Mirror, look like they were going to be staged simply. Then again, perhaps Ortega is showing early footage before the addition of dancers and singers. There's no way to tell.

The frustration -- beyond the greater one, that a tragedy prevented this concert from happening -- is not knowing what you're looking at. Where are Jackson and his conspirators at any given moment in the creative process? The film tries to be a concert film without having the actual footage. So when everything comes to a halt, audiences get thrown.

This Is It is not a sacred document, as Ortega asserted to the Nokia crowd. But it is a fascinating one. It shows a songwriter-performer who knows his material intimately. While not always certain what he wants, he knows it immediately when he gets it. At one point, Ortega asks his star how he will see a certain cue onstage. Jackson pauses and then says, I'll feel that.

And you know he would have.