So I have this stock footage of burning paper that I want to use to transition from one image to another. I have the image that it will transition to underneath and already keyed out that part of the footage. If you look at my example image, it shows the footage having white where i want the image that I'm transition from to be. So in short, how do I replace the white with an image... i tried screen and add modes with no luck. I ALSO want to keep the burning paper / flame / burnt edges detail. Any ideas? Prob easy for you AE masters...
Create a precomp with the footage you want to transition from.
Use the alpha from the keyed out fire transition layer to "cut" the transition in the video.
Comp the fire layer with Multiply, like Walter suggested, on top.
Use this precomp with the same alpha from the fire transition to get what you're after.
Duplicate the precomp in the project window to be able to replace the fooatge and have separate precomps for each transition.