This video is fucked up, man.
Here we have young Sadie sobbing uncontrollably at the thought of her adorable little brother one day becoming old and ugly, and of herself one day dying of old age. This is happening because some asshole has told young Sadie that everyone will one day grow old and die. This knowledge has clearly crushed Sadie, due to the fact that her small child-brain isn't exactly equipped to process the deep, inescapable sadness of the human condition.
Sadie's mom is a real jerk.