This problem probally has a very simple solution, but I am totally stumped. How does one make the user be able to slide or move(scroll) an image or clip to certain points? How can they go left to right in any order? When done right it looks as though the background or clip plays forward and backwards. If this question doesn't make any sense, kioken used this effect when they designed barneys.com a year or two ago. I want to know how they did it. Not the entire masking and layering look, just the user controlled slide left to right.

I'm lost and need help and direction. Scripts, advice will be greatly appreciated.

Thanks