Chromakey shader for movie textures?

I’m needing to replace a color in a movie (say, green) with transparency. As I can’t grab the pixels from a MovieTexture, I can’t brute-force it, but seems like a Shader would be perfect for such a task. I have chromakey code I like (used it in other projects).

Does anyone know of a shader that will do such color replacement? I’m no shader expert, but I can try, if there’s something close out there. Or if anyone would like to help me make one, we can talk revenue-sharing.

I found some code here, but it’s old and won’t compile in 3.5.
http://forum.unity3d.com/threads/11512-Using-a-texture-s-RGB-as-an-Alpha

FWIW I’ll be putting up such a shader to the asset store soon. You wanna beta test?

You can check out my shader based solution in the asset store: Universal Chroma Key Shader Universal Chroma Key Shader | VFX Shaders | Unity Asset Store

I hope you find it useful!