About 2.5 hours into the webcast, I hear someone come into the house, which is odd, because my only housemate is at work, and we aren't expecting anyone. I realize I didn't check to see if the doors were locked before starting the webcast. I hear the person stealthily moving around the house, and then I hear them stealthily climbing the stairs, towards my room. My door opens, and I hear an unfamiliar male voice say "Hello?". Then, after presumably seeing me sitting still and smiling in front of a camera, lit from beneath by a florescent bulb, he promptly descends the stairs and exits the house.

You can see this happen at 2:36:30.

As it turns out, the doors were locked, and he had broken one open. We found nothing missing, as there is not really anything of value in the house other than the laptop I was using to webcast.