Hong Kong is in uproar. Each weekend for the last two months, thousands of people have taken to the streets. Alvin Yueng, who leads the Civic Party, shares their fears. First, of a plan to given Beijing a greater say in extradition, then for a wider cause; defending Hong Kong's freedom. But as the local authorities struggle to contain the crisis, and Beijing's grumbles grow ever louder, could the People's Liberation Army be on its way?