The baby was later released from the hospital in stable condition. He's now in foster care.
Doctors at Cook Childrens Medical Center testified they put the baby in a room with a hidden camera because they suspected he was a victim of child abuse.
The child arrived at the hospital in July after he had stopped breathing.
At first, doctors thought he suffered from severe reflux -- when acid from the stomach backs up into the esophagus. The baby underwent surgery to correct the condition.
But a day or two later, he mysteriously stopped breathing again, Dr. Sami Hadeed testified.
Hadeed, a child lung specialist, said he was shocked at what he saw when he reviewed the surveillance video.
The video shows Scott placing a blanket over the baby's face for more than 20 seconds. A nurse briefly enters the room. Scott paces the floor and appears to check her cell phone.
The courtroom watched in absolute silence during what happened next.
The camera captured Scott covering her baby's face with her bare hand. At first, the baby kicks and fights back.
By the time she removes her hand one minute and 14 seconds later, the baby appears limp.
Seconds later, with alarms indicating the baby had stopped breathing going off, doctors and nurses rush in to resuscitate him.
Hadeed testified that the baby would have died had they not been there to help.
"I still get emotional," Hadeed told the jury. "I get night sweats when I think about it. I take care of the sickest of the sick. His life was being put in danger by someone who was supposed to take care of him."
Earlier Wednesday, jurors heard an audio tape of Scott's confession to Fort Worth detective Dennis Hutchins.
On the tape, Scott admitted to smothering her baby.
She said it was hard being a teenage mother, complained that the baby's father didn't help and added that she didn't want to deal with the stress anymore.
Doctors said it's not known if the child will have any lasting injuries from the lack of oxygen.
At one point under cross examination, Scott's attorney, David Jones asked Hadeed, "Was there an actual injury he suffered?"
"He suffered a significant lack of oxygen," the doctor answered. "It almost killed him."
Prosecutors in the courtroom of Tarrant County District Judge Scott Wisch rested their case late Wednesday.