I've never used this site or UStream because I don't understand what I'm looking at.

I just clicked on a video on Justin.tv's front page. I was shown a 3-second intro, and then a woman appeared, introduced herself and started talking.

Internal monologue: "Is this live? pre-recorded? I have no clue. The site seems to be about live video, but if so, how did I manage to tune in right as she was introducing herself?"

I refresh the page. See the intro again, and the video starts from the same point as before.

So it's not live. It's pre-recorded video...

Why wouldn't I just watch this on Youtube?

What am I missing here? The user experience on both of these sites seems really bizarre. They tell me I'm going to watch some live video...and link me to a bunch of pre-recorded stuff. It's bewildering.