Michael Jackson: This Is It, Kenny Ortega, 112 mins, (PG)Fleetwood Mac, MEN Arena, Manchester

The biggest musical event this week isn't a concert at all, but it's coming to a popcorn pit near you. By the time I'm writing this and you're reading it, Michael Jackson was meant to have performed 27 dates of his This Is It farewell show at the O2 in London, with a further 23 to follow in the spring.

Whether you believe he would even have made it this far without cancellations is a matter for personal conjecture. And it's a question that the feature film, cobbled together from his rehearsals at Los Angeles' Staples Center, only hints at answering.

The Star Wars scroll-up at the start tells us that This Is It was going to be "an entirely new concert experience". Entirely new? Not exactly. A very high-concept version of the existing concert experience, perhaps. But it's typical of the uncritical hyperbole that defines and dogs this documentary.

The main problem with This Is It lies in its choice of director: Kenny Ortega, the director of the stage show itself, who has cherry-picked the clips which make his production appear in the best possible light.

It would, unquestionably, have been a cracking concert: the dancers who pop up from below-stage at toaster speed, the black widow spider from which Jacko emerges in "Thriller", the appearance of an actual bulldozer for "Earth Song", the Zelig/Dead Men Don't Wear Plaid-style film preceding "Smooth Criminal" in which MJ is placed inside a montage of film-noir scenes (admiring Rita Hayworth in Gilda, dodging Bogey's bullets in Dead Reckoning, and so on).

But had the footage fallen somehow into the hands of an impartial documentarian, we might have seen a completely different film from the hagiography Ortega has given us.

The most fascinating scenes, nevertheless, are the candid moments in which Michael, bespectacled and studious, chomping on snacks or sucking on a lollipop, supervises auditions, oversees choreography on his laptop, bosses the band (who all call him "Sir") into making it "more funky" and admonishes them for "not letting it simmer!", while emphasising that his criticisms are always delivered "with the love, L.O.V.E".

His face, it's sad to say, looks like someone who's been in a fire, but his physical condition isn't as poor as one might expect. The 50-year-old was still super-mobile, as the awe-inspiring spin he throws into "The Way You Make Me Feel" proves, and his voice on "Human Nature" is out of this world. What he lacks, it seems, is stamina: he complains that he needs to save his voice rather than rehearse the outro of "Just Can't Stop Loving You", and can't hack a retake of the routine for "Beat It". Interestingly, the one character we never meet is Dr Conrad Murray, dosing Jacko up and pushing his body to the limit to meet AEG's concert schedule.

Despite the stress he's under, at no point does the King of Pop kick off, throw his toys out of pram or reach the end of his tether. Instead, he spends his down-time delivering a softly-spoken soliloquy on climate change. Maybe he really is that saintly. We'll never know, because Ortega's sometimes inspiring, but mostly somewhat sad film is ultimately – no apologies for the pun – a whitewash.

If she didn't mean it, it wouldn't work. Stephanie Lynn Nicks may have been working as a waitress in a cocktail bar when Fleetwood Mac found her, and cleaning the producer's toilets to pay for her first record, but the buck-toothed blonde from Phoenix never stopped imagining herself as a Welsh witch goddess.

Thirty-five years on, she hasn't ceased: swishing about in a bat-winged cape and a diamante half-moon pendant, and bleating about a "woman taken by the sky". Mystery-and-magic isn't merely an act for Stevie. She believes it, and bless her to bits for that.

If Stevie on a British stage is what really sends the hackles tingling for the faithful, then it's only in the context of a truly stunning Fleetwood Mac concert. Her foil and sometime lover Lindsey Buckingham, spindly-legged and still offensively handsome, is a fast-fingertipped phenomenon on guitar. His solo spots for "Big Love" and "Oh Well" are breathtaking; the title track of his 1979 folly Tusk is so berserk you can almost taste the Hollywood A-grade in your septum.

Together, they conjure such an electricity that the rhythm section John McVie and Mick Fleetwood, whose British blues band was transformed by the Buckingham-Nicks takeover in 1974, can only stand and watch. "I think I had met my match," she sings in the sublime "Sara", and she looks at him with lazy eyes. He catches the glance, and bites his lip. As the song ends, they waltz and he kisses her hair. It must drive their current partners insane. Because it sure as hell sends a shiver through everyone else.