intro video? Javasript?

[Lab860]

Has anyone seen websites where there's like a video of someone walking out on your web page and talking, pretty much describing your services etc. It looks like Javascript the way they stand and talk in front of your main page, does anyone know what this is called? I wish I had an example website to show you, but I don't, I sort of randomly bump into it, I can't think of any sites that have it.
I just wanted to know what it's called, the technology it uses so I can look into it, what do you think about this? is it corny? is it good marketing?

[Lab860]

ok I found one, triad web design. the video guy comes out in a few seconds.
What is this called?