found on perezhilton.com

Michael Jackson fans might be a bit upset over this revelation.
The much hyped-about This Is It flick, documenting Michael's final tour rehearsals, seems to have gotten a bit of help from the past.
According to new reports, music experts are claiming some of the sound bytes you hear are actually from years before!!!!
Former BBC senior studio manager Andrew Rose is one of those claiming the film used old clips. Such as when Jackson sings Earth Song, it's actually old vocals from one of his demos.
Rose claims, "Throughout the film sudden changes in vocal timbre
suggest the dropping in of older recordings which may have required
significant digital manipulation to fit the new live backing."
But the most shocking part? Officials at Sony Pictures are admitting to altering the film!
Sony spokesman Jim Kennedy says, "In order to fulfil Michael's
vision for his fans and his children… the filmmakers had to incorporate
some pre-existing materials, including vocals, where the rehearsal
footage audio was incomplete and/or inaudible. In addition, usage of
master recordings (such as Earth Song) was credited in the end titles."
This is It has grossed over $200 million already.