Veryan Khan, editorial director for the Terrorism Research and Analysis Consortium, said that the light source on the men in the latest videos appears to be coming from two different directions — as opposed to one bright sun. If the video was made outdoors in natural light, the shadows behind them should be going in one direction. Instead, they converge.

“The hostages are visibly bothered by” the bright light, she said.

One of the hostage’s jumpsuits flutters in a breeze, yet Khan said she believes it’s from a fan. Wind in the desert would be noisy and affect the sound quality of the statements being made by the knife-wielding man, she said. It would also kick up dust, and none seems apparent, she said.