Exceptional Demand curves ( exceptions to the law of demand)

This video explains exceptions to the law of demand, it also explain two situations where price falls and quantity demanded falls this is the case with giffen goods and expectation future fall in price and another situation where price increases and quantity demanded also increases that is the case with goods of ostentation and when consumers are expecting a future rise in price. for the law of demand for the link below why the demand curve slopes downward....