How is this done? (images moving with a scroll bar)

[kehe]

Hey, I'm new here, Tried not to make my post vague, but didn't know how to phrase it.

I was just wondering how the product reel at http://store.steampowered.com/ worked.

all I can see is a collection of images and not the logic behind it :/

If I wanted to try and make something like this what would be a rough way to go about it?
initally I thought maybe an iframe could hold all the images next to each other, and try and use javascript to increase the value of the slider over time, so it scrolls by itself.
That said I've never used an iframe and my knowledge of js is limited.
but I have put some thought behind it.

Any help would be appretiated as I've always found it to be pretty clever, any similiar things would be appretiated aswell, just to see them.

thanks.

[FreshpageDesign]

Jquery would be the way to go http://sixrevisions.com/tutorials/javascript_tutorial/create-a-slick-and-accessible-slideshow-using-jquery/