In the video of Riley Cuskey's death there is not nearly enough blood spilled to cause a healthy person to die. If the femoral artery is severed blood flows out as if from a hose. Death is very quick, a few minutes at most.
Cassandra's doctor incorrectly states that wisdom teeth only erupt in adulthood. While it is true that in most cases wisdom teeth only erupt after age 17, they can erupt much earlier. - The doctor didn't say "only", she made a generalized statement that they come in during adulthood and was a clue which lead to a further examination.