Very nice moving the background

good afternoon
There is such a wonderful site-with a wonderful slider
http://britishdesign.ru/?lang=eng
wait for a while - and there will be movement))
as I understand it - there is one picture - the background - a movement - a bunch of individual photos - over a background
tell me - is it possible to do so with our slider?
that is, to change the only moving part - and not the whole picture at once.
it's beautiful, and it's faster to boot and vyglyadit- until esche- not zamylennye)
if you can not do- so that it may be wise to make such a possibility?
thank you

Hi

This is very nice, but complex way of doing this. I think using moving GIF would do the same effect and is much easier to implement.