For more than two decades, the U.S. position has been that al Qaeda acted alone on September 11th, but a newly public video has raised questions about whether the Saudi government provided crucial assistance to the hijackers during the 9/11 terror attacks.

Omar al-Bayoumi, whom the FBI says was an operative of the Saudi intelligence service with close ties to two of the 9/11 hijackers, can be heard on the video, which was unsealed in federal court this week and obtained by 60 Minutes.

The 1999 video was taken within 90 days of the time when senior al Qaeda planners were deciding on 9/11 targets, Richard Lambert, a retired FBI agent who led the initial 9/11 investigation in San Diego, said.

Lambert, who's now a consultant on the case filed by the families of 9/11 victims to hold Saudi Arabia responsible in the Sept. 11 attacks, said knowledge of where the Washington Monument is in relation to other D.C. landmarks could help guide people toward intended targets.

Lawyers for the 9/11 families and former intelligence analysts who spoke with 60 Minutes believe portions of the video show Bayoumi surveilling the Capitol as part of that plan.

They also seized Bayoumi's hand-written address book that the lawyers for the 9/11 families say was filled with phone numbers of numerous senior Saudi officials who were in the government at the time.

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