Can Someone Please Tell Me How This Was Done

Hey everyone,
I have a question i would really like some help with. I have a client who has seen this website http://www.dunwoodie-architectureand...co.uk/main.php and would like me to design something similar as far as the elastic centring goes. I know this would of had to be done with actionscript but i am not sure how. If someone could help me to re-create this it would be much appreciated. I am able to do it with frame animation but im thinking AS would be alot better option.

Thanks in advance