[smug] I knew this, and dd knows this - when she was 3 she asked me if a kangaroo was a mammal, which flummoxed me, because of the business of how it gives birth, but in actual fact, being a marsupial is a subset of being a mammal. Dd freaks random people out by telling them randomly that 'a kangaroo is a special sort of marsupial, called a mammal, it is a mammal because it doesn't lay eggs, and the baby drinks its mother's milk, the baby is born very small and climbs up its mummy's tummy to the pouch'.
She is a bit strange....
Lovely lovely video - dh has just gone all soppy over it!!!