Only two days before his death, Michael Jackson was energetically rehearsing for a string of comeback dates, according to newly released video.

In the video, Jackson is seen singing "They Don't Care About Us" at Los Angeles' Staples Centre, backed by his band and a team of dancers.

The Staples arena will be the site of a public memorial event dedicated to the singer on Tuesday, according to sources close to negotiations with the city.

The video was released to CNN by AEG Live, the concert promoter behind Jackson's 50-date "This Is It" comeback stint, which was to be held at London's O2 Arena.

The video, shot June 23, was released amid accusations of drug abuse and theories the singer was too weak to make it through a rigorous rehearsal schedule.

Meanwhile, a judge has delayed a custody hearing for Jackson's children at the behest of the singer's mother Katherine Jackson and his former wife, Debbie Rowe.

Katherine Jackson will retain custody of her grandchildren until the hearing, set for July 13.

Earlier in the day, Rowe reportedly told a television station that she would seek custody of Prince Michael, 12, and Paris Michael Katherine, 11.

Rowe said in a telephone interview with KNBC in L.A. that she will also seek a restraining order to bar the children's grandfather, Joe Jackson, from seeing them.

Rowe added that she would like to keep Jackson's three children together, but the singer's youngest child has a different mother, the station reported.

The news comes a day after Jackson's will was filed in a Los Angeles court. It revealed the pop singer had entrusted his entire estate to his family while cutting Rowe out.

And earlier in the day, President Barack Obama said that he is a massive fan of the singer.

"I grew up on his music -- still have all his stuff on my iPod," Obama told the AP on Thursday, adding that Jackson "will go down in history as one of our greatest entertainers."

Obama said he was pleased that Jackson is now being remembered for his music and not his controversial personal life. "I think that his brilliance as a performer also was paired with a tragic and, in many ways, sad personal life," Obama said.

DEA probes death

The U.S. Drug Enforcement Administration is joining the investigation into Michael Jackson's death, say reports, but it remains unclear why.

The Associated Press says a law enforcement official has told them that the DEA is stepping in at the request of the Los Angeles Police Department.

It's not clear why the agency is being brought in, but the agency might be required to provide expertise in investigating drug abuse, and substances local police may not be familiar with, such as prescription medication.

The DEA could also play a role in looking at Jackson's doctors, the drugs they prescribed and whether the doctors were registered with the DEA to prescribe those substances.

Also, investigators are expected to look at the sources of the drugs provided to Jackson or his associates to determine if there was a pattern of trafficking.

Following Jackson's death, allegations emerged that the 50-year-old King of Pop had been consuming painkillers, sedatives and antidepressants.

Will leaves estate to family

New Jersey family and estates lawyer Janet Pennisi says the will, completed in July 2002, is actually quite ordinary.

Jackson's 79-year-old mother, Katherine, is named as the beneficiary of the singer's trust and the chief guardian of his three children.

The will also names singer Diana Ross, 65, as a successor guardian for the children and their estates if anything occurred to their grandmother.

With files from The Associated Press