'I love how the stewardesses do it,' he says. 'I love it!' It's a moment that illuminates not just the way Jackson danced or sang, but how he thought -- viewing the world in terms of movement, human semaphore. 'This Is It' offers only a few such insights into Jackson's artistic process, though enough surface to make this a useful document, as well as a beautiful one. Mostly it's a tribute to the power of Jackson's body and voice, which the film presents as surprisingly intact despite his age, 50 at the time of his death, and the various ailments that reportedly had plagued him in the preceding decades. Differing greatly from the rough, casual mood of many behind-the-scenes pop docs, this one is instead of a piece with Jackson's body of work: dazzling and strange, blurring the line between fantasy and reality. As a tragic teaser for the shows that might have been, 'This Is It' hurts. If Jackson had been able to perform as he frequently does during these scene, he would have accomplished the comeback for which he was so hungry. Though occasionally ragged, his voice is strong -- lush on ballads 'Human Nature' and cutting in rockers like 'Black Or White' and 'Beat It.' And his dancing is utterly assured. It's tough to believe he was 50, he seems so feather-light and vigorous. The special effects and short films made for the O2 shows also delight. 'Thriller' gets an update that takes the legendary video's graveyard scene into the Tim Burton era. 'Smooth Criminal' inserts Jackson into the classic Hollywood films he loved -- from 'Gilda' to 'In a Lonely Place.' There are aerialists, 'pole dancing specialists,' arcs of fire and one adorable little girl. Ortega has assembled this film to bewitch the senses, rather than to expose the inevitably tough realities of a rehearsal process. The film's prologue states that this footage was meant for Jackson's personal library, yet it's hardly raw. It's lit and edited like a real concert film, and the sound is almost too good to believe. Jackson does very occasionally slip up. The gaffes and vulnerable moments are welcome. Complaining about the newfangled ear monitors he's forced to wear, or chiding his dancers and band for encouraging him to sing in full voice when he should be conserving his instrument -- 'I shouldn't be singing out, I am trying to warm up my voice to this moment, why are you doing this to me?' he exclaims, seeming truly abashed. The great artist is just a man, slightly anxious about this momentous and risky return. But such intimate views, so common in rock-doc favorites like 'Gimme Shelter' or Metallica's 'Some Kind of Monster,' are not the point of 'This Is It.' Ortega made this film to honor not just the memory of Jackson but the hard work of a big cast and crew that never made it to opening night. The film opens with emotional interviews with the dancers, apparently done while Jackson was still alive, about how excited they are to work with him; at times it threatens to veer off into 'Fame' territory, celebrating the starry-eyed kids whose efforts lifted up their hero. Ortega is obviously aware, however, that the overwhelming draw is the footage of Jackson himself performing. 'This Is It' always returns to those sequences, which don't exactly surprise -- Jackson had his moves, and he stuck with them -- but always impress. Here's the King of Pop throwing himself on the floor during 'Beat It,' re-enacting the impish courtship dance of 'The Way You Make Me Feel,' doing the Soviet stomp in 'They Don't Care About Us.' His solo dance during 'Billie Jean,' complete with slow-motion crotch thrusts, is breathtaking. 'At least we get a feel for it,' Jackson murmurs afterward. These sequences are simply beautiful, driven by Jackson's anomalous grace. They sometimes feel enhanced; a split screen makes the dancing more magical, and a careful sound mix hides most of the roughness for which any middle-aged singer must compensate. Jackson's total lack of engagement with the cameras adds to the unreal mood. He's always performing, but for the imagined masses, not for the filmgoer. Not reaching those masses was the final tragedy of Jackson's life. Occasionally, he's shown offering creative direction to his collaborators, and the steel in his voice reveals how much the world he was creating onstage meant to him. Everything, really: enough to push himself to the edge of human endurance. 'This Is It' doesn't acknowledge that reality, and that's a little odd. But Jackson probably would have wanted it that way. 