The treasure trove of material, along with possible insurance proceeds and ticket sales to memorabilia collectors, could help benefit the late singer's estate, which is burdened by an estimated US$400 million in debt.

“He was our partner in life and now he's our partner in death,” Randy Phillips, president and CEO of concert promoter AEG Live, said in an interview at Staples Center.

Jackson had been rehearsing for a giant series of comeback shows in London.

“If we all do our jobs right, we could probably raise hundreds of millions of dollars just on the stuff we have worldwide and then the estate could eradicate its debt.”

AEG Live also stands to profit from the material. Jackson's album sales have exploded since his death, with three of his albums in the top three spots and 2.3 million tracks downloaded in the United States, Nielsen SoundScan said. Worldwide digital downloads for the week hit 3.3 million.

The clip released Thursday shows Jackson dancing and singing to “They Don't Really Care About Us” on June 23 during a rehearsal at Staples Center. He died two days later at age 50.

Phillips said he released the clip because he was tired of seeing the singer negatively portrayed in the media since his death.

“I said let's grab one piece where we can show people where he was headed,” he said. “He was developing getting his moves together.”

The rehearsal footage, shot in high definition, includes Jackson performing his hits “Thriller” and “Beat It.” Other footage shows production meetings and auditions.

“We have enough audio to make two live albums, and he's never done a live album,” Phillips said. “This is really the last great work of a 21st century genius.”

The production budget for the 50 London shows, which were set to begin July 13, swelled to more than US$25 million, he said.

Part of those costs included 3D technology used to produce what Phillips called “mini-movies” involving “Thriller” and “Earth Song.”