What Caused This iMac To Suddenly Start Smoking?

What caused this iMac to suddenly smoke from behind? A reporter at Chinese tech news site, cnBeta, says he was chatting away when white smoke started to pour out. Here’s the video he captured with his iPhone:

Yeah we’ve heard stories of exploding iPods (like this UK girl’s) but I’m not saying this is part of some trend or anything. I just wanna know what you think happened here.

Looks to be enough air flow there…it’s just gotta be one of those rare screen failures, right? You tell me. [cnbeta (translated) via Cloned In China]