Fighters from the Salafist Group for Preaching and Combat, which would later become an official branch of Al Qaeda, perpetrated the 2003 kidnapping. Their leaders came from Algeria’s northern coastal region and were not used to driving in the sands of the Sahara, said the hostages. The jihadists grabbed tourists from Germany who were traveling on motorcycles, but did not know how to operate the bikes. They forced the tourists to drive with a gunman riding on the back of the seat.

The leader of the operation, Abderrazak el Para, whom the French news media called “the Bin Laden of the Sahara,” appears almost giddy the first time he mounts a motorcycle. His European captive — apparently not yet aware that he has been kidnapped — shows him how to stand up properly in the seat.

“This video shows, No. 1, the lack of sophistication of the jihadists,” said Mr. Atallah, who reviewed the video. “It also crucially shows that they were ad-libbing. They had never done this before.”

Ingo Bleckmann, a 60-year-old inventor from Salzburg, Austria, initially thought he was being robbed when the militants confronted him. He said he quickly realized he was in the hands of ideological extremists.