HariesDesign.com - It a simple flash animation. Create Masking layer in flash, it looks nice with different color.

Step 1
Create a new project with 300 x 220 px
Step 2
Insert image 1 to layer with color picture
File > Import > Import to Stage
and
Insert image 2 to layer with Black and White picture
Now look at the position of layer be like this :
Step 3
Create a new layer " mask ", and insert with rectangle shape and change layer position
Step 4
On layer mask,convert frame to symbol, movie clip
loadposition ads-336x220}
And then Create motion on layer mask
Step 5
Make "layer mask" to be Mask types, klick on right mouse botton and choose Mask menu
Now you get layer and position like this:
Done!Preview press Ctrl+ENTER !