How to watch The International 2 Match Online:
1. Download steam from here.2. Create Login id.
3. Visit Dota 2 app page on Steam.
5. Install the Dota 2 Spectator client.
6. Enjoy, By using DOTA 2 Spectator client you can watch live matches, recent matches and list of the upcoming matches which are about to showcase.
The International DOTA 2 tournament is set to start from 31st August 2012. The matches will be available on steam client direct from Beyora Hall. The more updates related to spectator client will be added exclusively online here.
Source : Here