[LINK] How do you do this?

Hi there, I have a pretty straightforward question.

I’ve seen several sites where the animation is all over the screen, but without any stretching when resizing the window. So I was wondering, if you make a site like this, do you have to use a document/canvas that’s 1600*1200 in size or what?
That doesn’t seem very pleasant to work with? A lot of scrolling, no?

For example: http://www.endrone.com/