Why Does the the AAP Discourage Media Use by Children Younger Than 2?

In the video below, Dr. Ari Brown explains the research behind the American Academy of Pediatrics (AAP) recommendation of limiting media use by children younger than 2.
Three questions are answered:

1. Do infant-directed programs have any educational value?
2. What harm has been found in children under age 2 watching TV shows?
3. What harmful effects have been observed from children under age 2 being exposed to secondhand TV (background media)?

As part of the third question, researchers have found that if a TV is on with an adult show, a child under 2 will look up at the screen 3 times per minute (every 20 seconds). No wonder kids who are playing in a room that has a TV on are not as engaged in their toys!