From Australia to Hong Kong, one side of the world welcomes 2009 with fireworks displays.

The video begins with a brief introduction and greeting, setting a positive tone for the content.

What is the initial part of the transcript focused on?

• A complex mathematical problem

• A historical event

• A detailed explanation of a concept

• A brief introduction

What is the main theme of the second section?

• Discussing a scientific theory

• Explaining a historical event

• Greeting for the New Year

• Describing a natural phenomenon