How do you do a basic image mask in the Video Sequence editor?
I have two images that I want to mix together using a third image, where the black pixels will mean showing the first image, and the white pixels showing the second. Like so:
(First and second images mixed using the third image, the mask, resulting in the bottom image)
This is trivial in the compositor, but I have several dozen shots to do this for so I'd rather not make a mess of scenes and compositing. How can achieve this same result inside the VSE alone?