If you watch the video closely, you'll see the person with the cognitive ability moving the balloon to follow the random movement of Terri's eyes.
It was a bit crude, but Bill Handel (KFI) likened it to the frog in that famous WB cartoon -- whenever everyone left the room she would jump out of bed singing "hello my baby!"
The "balloon" video showed someone with no cognitive ability whatsoever.
If you watch the video closely, you'll see the person with the cognitive ability moving the balloon to follow the random movement of Terri's eyes.