First the result:
Sort of neat and very easy to do. No code is actually involved. The alpha mask is a FLV movie created in After Effects. The card wipe effect is a standard effect in AE. Creating the file took me less than five minutes. I just dropped a white solid into a 1-sec composition, added the card wipe transition effect to it, set the back layer to none, and set the completion to 100% at the beginning and 0% at the end. I used mostly the defaults but there’re quite a number of options you can ticker with. You can make the cards flip in a more disorderly manner by introducing a random delay, for example.
Things were slightly trickier on the Flash side. After embedding the FLV, I dropped movie into an movieclip named “cards”. In a second movieclip, I put the image to be transitioned-in on the bottom layer and put “cards” on a layer above it. In Properties > Display, I set the blending mode to “Alpha.” This applies the alpha channel of the FLV to the layers below. To get the shading of the cards applied to the image, I duplicated this layer and changed the blending move to “Multiple.” After doing all that, I dropped the container clip into the main timeline over another image and set its blending move to “Layer”–alpha blending happens only when the parent movie uses layer blending mode.
The same technique works for some other AE transition effects as well. Here’s the twister effect:
More than one effect can be used at the same time. Here’s the card wipe with the twister effect: