In this flash tutorial the instructor shows how to make a black and white mask animation. To do this, first start by importing your image into the flash tool and bring it on to the scene. The image should be wider than the scene. Now select and distribute the layers. Now convert those images into movie clips. Now go to frame 80 and add all frames. Get back to the first layer and create a shape that is the your mask. Now go to frame 40, select key layer and add free transform tool. Now, mask the layers and make sure they are unlocked. In frame 80 add key frames and move images using left arrow keys. Finally adding motion to it generates the desired effect. This video shows how to make black and white mask animation in flash.