Earlier quoted context omitted.
There were a lot of trojans with chat like that. An even nicer chat was with The Matrix green letters behind it or just plain black/green. The most common way to get infected is running infected applications. As for your webcam, did it not have a light when on? Also, very likely it was your cousin or someone you know.
I don't recall mine having a light. It definitely wasn't my cousin. It may have been something malicious I installed without knowing. Maybe I downloaded and installed something from Kazaa or whatever the current P2P file sharing network at the time. I thought it was weird that it happened right after I exited Diablo 2 though.
I'd suspect you were playing with someone you know Diablo 2 and they just decided to mess with you a bit.