In the May 2004 attack, militants dressed in military-style uniforms opened fire inside two oil industry office compounds, then moved to an upscale residential area. They took 45 to 60 hostages.

Saudi security forces stormed the complex, but three of the militants escaped, including al-Nashimi. Twenty-two people were killed in the 25-hour rampage, almost all of them foreigners, including one American.

Al-Nashimi was killed the following month in gunbattle with Saudi forces.

The Khobar assault was one of a series of attacks against foreigners by al-Qaida's Saudi branch in 2003 and 2004, aimed at undermining its U.S.-allied royal family.

If the statements on the new video are true, they would also fill in a missing piece of the puzzle of the attacks on Sept. 11, 2001.

U.S. counterterrorism officials have believed for some time that the original 9/11 plot included another hijacker on United Airlines Flight 93, which only had four attackers. The two planes that flew into the World Trade Center towers and the one that flew into the Pentagon each had five hijackers.

Federal agents at first thought Zacarias Moussaoui was intended to be on Flight 93, but later revised their allegations. Moussaoui further muddied the waters during his terrorism trial, when he claimed -- and later recanted -- that he was supposed to fly a fifth plane on Sept. 11 into the White House.

During a May audio message, Osama bin Laden said Moussaoui was not the 20th hijacker "as your government has claimed." He didn't provide the actual identity. Moussaoui pleaded guilty to conspiring with al-Qaida to fly planes into U.S. buildings and is serving a life sentence at a federal prison in Colorado.

The Sept. 11 commission identified yet a third person as a possible 20th hijacker: al-Qaida member Mohammed al-Kahtani, who was turned away at Orlando International Airport in Florida in August 2001.