The post by Biggs, who went by the screen names "CandyJunkie" and "Mr Biggs", was initially ignored by the forum moderators because they though it to be a prank.
However, there were other users who posted insults, even egged him on.
The teen streamed footage from his bedroom using the "lifecasting" website Justin.tv, which has been designed to let netizens share the minutiae of their everyday lives.
Media reports reveal that Biggs took several pills before lying on the bed with his back to the camera.
When he did not move for a few hours, people watching the even realised that it was a serious matter. Moderators then traced Biggs's location and informed authorities.
The webcam was still on when the police entered Bigg's room, and was later covered up.
The teen described himself as a "good hearted guy" on his social networking profile.
"I care a lot about my friends and my family and I would do almost anything for them," news.com.au quoted him as having written on his profile.
"I am very goal oriented, I know what I want to do with my life and I am working towards it," he wrote.
Just a week before Biggs took his own life, he had left a message about closing a chapter in his life and apologised to his friends for his behaviour.