"Am I really going to die?" a student says at 0855 local time - the same time a crew member on the bridge made the first distress call.
Students ask whether the ship will sink. Where their teachers are. "What's the captain doing?"
Three times they are warned over the loudspeaker to stay where they are, even as the tilting increases and it becomes less possible for them to go anywhere else.
The video was on the mobile phone of 17-year-old student Park Su-hyeon, when rescuers recovered his body.
The boy's father, Park Jong-dae, provided it on Thursday to The Associated Press, saying he wanted to show the world the ship's condition as it sank.
Park senior earlier released it to select South Korean media.
