A previously unseen videotape filmed more than a year before the Sept. 11 attacks and shown publicly for the first time Sunday captures a jovial Mohammed Atta, the plot's ringleader, appearing with the hijacker who would later pilot United Airlines Flight 93.

Atta and Ziad Jarrah, laugh and smile on the hourlong video, released by the Sunday Times of London on its Web site.

Click here to read the Sunday Times' story.

Yosri Fouda, the author of the story and an investigative reporter for Al-Jazeera, said it is the first time any footage of a Sept. 11 terrorist pilot had been found.

"It should have been released a long time ago, that's my position, but better late than never," Fouda told FOX News. "What I find really significant about this tape is that it fills in a vacuum in the understanding of the plot to what we've come later to know as 9/11."

Fouda declined to tell FOX News how he obtained the video, which he said was made in Afghanistan for release after the terrorist attacks. The time stamp on the clips of Atta and Jarrah dates it to Jan. 18, 2000.

Attah and Jarrah appear far different than in their mug shots made famous after they were identified as the attackers who hijacked planes that crashed into the World Trade Center and a Pennsylvania field five years ago. Both are bearded. They seem younger, and Atta's infamously bleak gaze is replaced by a somewhat softer expression.

The video also contains footage of Al Qaeda leader Usama bin Laden speaking to a large audience, including children.

The British newspaper said the tape was recorded on two different days in Afghanistan in January 2000, and was obtained "through a previously tested channel," giving no further details. The newspaper said the video had been authenticated, on condition of anonymity, by sources from Al Qaeda and the United States.

A U.S. intelligence official, who declined to be identified, citing government protocol, told The Associated Press, "We're aware of the tape and we're reviewing it." The official declined to answer further questions.

The Sunday Times said the footage was taken in Afghanistan and was meant to be released after the men's deaths.

It appears to be a departure from previous releases by Al Qaeda, which is "normally, very professional in their media," said Paul Beaver, an independent defense and security expert.

It did not appear on Web sites commonly used by the group. The newspaper quoted an unidentified American source who said that lip readers had been unable to decipher what the men were saying.

The newspaper said the hourlong video was made at an Al Qaeda training camp in Afghanistan, is dated Jan. 18, 2000, and contains the only known footage of Atta and Jarrah together.

Ben Venzke, head of the Virginia-based IntelCenter, which monitors terrorism communications, said the video was probably raw footage that Al Qaeda had intended to edit into a package similar to one released last month showing the last testament of two of the Sept. 11 hijackers, Wail al-Shehri and Hamza al-Ghamdi.

For more than 30 minutes, the video shows Atta, who flew one of the planes that brought down the World Trade Center, and Jarrah, who piloted United Airlines Flight 93, which crashed into a Pennsylvania field, sitting in front of a white wall, alternately alone and together.

The Egyptian-born Atta is wearing a dark sweater and pats his hair into place after trying on a hat for the camera. At one point, the camera pans out to show a machine gun leaning against the wall next to him.

Atta appears to be the more reticent of the two hijackers. During a portion of the tape showing them together, the Lebanese-born Jarrah laughs and smiles broadly as Atta shakes his head slightly. The conversation then seems to turn serious, and the tape shows the two sitting on the floor, hunched over papers, which The Sunday Times reported was Jarrah's will.

Bin Laden said a few years ago that he was saving Atta's last testament to release for a special occasion, Venzke said.

"It is highly unlikely that Al Qaeda wanted the material to be released in this manner, and it is not consistent with any previous release," he said.

Diaa Rashwan, an Egyptian expert on militant groups, said he found it strange that the cameraman focused not only on bin Laden but also on his audience. He said normally Al Qaeda videos of bin Laden just focus on him.

"Was this a video by Al Qaeda or by a security agency?" Rashwan asked. "I have never seen such a video."

Although the video has no sound, it could contain valuable information, Beaver said.

"It helps build up a profile, so you can ID people in the future," he said.

But Robert Ayers, an international security expert, said the tape was more curiosity than valuable resource.

"The fact that these guys changed their facial appearance? Any actor on any stage in the world knows how to change their appearance, so why are we so surprised these guys changed their appearance?" Ayers said.

Previous mug shots released of the two men show them clean-shaven and with closely cropped hair.

The video also includes images of a man who appears to be bin Laden speaking to an audience outdoors. A time stamp indicated that footage was shot on Jan. 8, 2000, and The Sunday Times said it appeared to have been made at Tarnak Farm, once the base for bin Laden's family in the Afghan desert near Kandahar's airport.

It shows about 75 men, many in turbans or caps, sitting on the ground as bin Laden arrives to address them. A few children are in the crowd. The man who appears to be bin Laden stands in front of an expanse of bare dirt dotted with a few trees and windowless, one-story mud-colored buildings, some of them partly in ruins.

He appears calm, with a long beard and a tan cloak over a white robe that covers his head. He speaks for more than 10 minutes, although the camera frequently cuts away from him and onto the audience.

The Sunday Times said those shown listening to bin Laden included Ramzi Binalshibh, who allegedly helped plan the Sept. 11 attacks and is now being held in the U.S. prison camp at Guantanamo Bay, Cuba.

Also reportedly present was Nasir Ahmad Nasir al Bahri, a security guard who The Sunday Times said has claimed he was authorized to shoot bin Laden in the head if the leader was in danger of being captured.

FOX News' Sara Bonisteel and Amy Kellogg and the Associated Press contributed to this report.