MegaSack DRAW - This year's winner is user - rgwb
We will be in touch
At a guess, use Javascript to reposition the background image based on page scroll position? But please don't, it's really annoying.
That particular effect didn't work in Firefox - I had to open Chrome to see it.
Agree that it's annoying, although there's a very subtle version on pinkbike photo epics that is slick.
Lots of plugins for JQuery that will do this type of thing.
Look up 'jquery parallax' for example.
Yep its called Parallax. They can be very subtle or very immersive, but the effect is fairly short-lived before it becomes irritating and switches off viewers.
Loads of the kickstarter type websites use this model for their marketing...its good for minimalist, concise websites.
You can achieve it with pure CSS3 – https://codepen.io/scottkellum/pen/bHEcA
The original example linked is particularly grating. Let's suppose that I actually want to have a look at a picture of the subject of the story (a bit hypothetical, but hey, it is a story about him). I start off with a picture showing just his chin, and by the time I scroll enough to reveal his face, his forehead is cut off at the top of the window.
Maybe it has a place if the background is just for decoration, but it's not the way to present real content.
AS above, called parallax - theres a million free plugins and bootstraps and codepens to achieve it.