"Max...no post software for animation has been chosen yet. Are you saying that if I get Mimic to place the facial animation "close" I can fine tune it in After Effects or some such?" Well, what I'm saying is, you can render your face animation in Poser as per normal, with no video overlay at all. Then, bring the rendered video into a capable post editor (like AfterEffects) and overlay the second video track on the face in there, just like you can overlay a still image over another still image in Photoshop... using blend, transparency, difference, etc. The result would be easier to come by, and would probably look better than struggling to achieve the effect from the renderer alone.

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Tools :  3dsmax 2015, Daz Studio 4.6, PoserPro 2012, Blender v2.74

System: Pentium QuadCore i7, under Win 8, GeForce GTX 780 / 2GB GPU.