This clip illustrates ocean currents and the factors that affect them. It mentions that there are both surface currents and deep sea currents, which make up 90% of the ocean's water. It also explains how the Earth's rotation causes phenomena such as the Coriolis Effect.
Bill explains how the ocean affects climates in different parts of the world. He mentions the Gulf Stream and how it keeps Britain much warmer it would be otherwise. He also explains El Nino and how it affects the climate of the Americas.