Why are these endangered moths swarming Australia's east coast?

Why are these endangered moths swarming Australia's east coast? To play this video you need to enable JavaScript in your browser. Why are these endangered moths swarming Australia's east coast? The sudden influx of Bogong moths along Australia's east coast has caused a stir in cities like Sydney and Canberra, with people filming them infiltrating their homes and cars. The BBC's Helen Livingstone explains where they came from, and why there are so many.