How to-sliding menu with moving images below

Hello, this is my first post here.

Im trying to achieve the same effect with the sliding menu showing pictures and moving its position. Heres what im trying to do:

You can see when you position the mouse on the buttons “movement, illustration”, etc you can see below the buttons a “sliding menu” effect showing pictures and if you move the mouse to the next button it follows it. Ive tried the tutorial Sliding Menu posted here but the “mask” doesnt move, and thats what im trying to do here.
I can post the .fla sample ive done but is the same as the tutorial (sliding menu).

I would appreciate any help, ive been trying to do this for a while but is not working. :-/