Direct3D and Alpha Masks, impossible?

[wagenheimer]

Why can't you integrate the mask as an alpha-channel in the same image?

Because this image comes from a Running Video! =)... I need to use the video with Transparent Alpha. On original video file, on the left side of the video I have the colored image, and on the right side I have the mask! I think it is not possible to have ogg videos with alpha-channel on it, but somehow this game does the trick using these kind of masks!

I'm sure this is possible of doing without using shaders, because I got this video from a game which does not use shaders. But I'm trying to figure out how it's done!

[LP]

I'm sure this is possible of doing without using shaders, because I got this video from a game which does not use shaders. But I'm trying to figure out how it's done!

Other than multitexturing, the other approach I can think of, is rendering first image on the render target (which has alpha-channel) without affecting alpha, then rendering the second image affecting only alpha channel. Then, the resulting render target is drawn on the screen,