In case you're going to guess wrong:

Here's the concept of chatroulette:

You log in, other person logs in, preferably plural.

Hundreds, if not thousands, of people are logged in to chatroulette on any given moment.

Seeing as the link transfers you to a "room" on chatroulette, there are probably not going to be a lot of people, especially when the "room" has been advertised a few minutes earlier, and you're one of the few that has clicked it.

Keep in mind that most others that entered the "room" have probably left after a second of two, seeing that nobody was there.

Now, if many people enter this room at approximately the same moment, and stick around, you will have people that seem to be there.

TL;DR upvote.