Maya to AE: Video Screen Tutorial Anywhere?
 

I would appreciate help. My goal is to add video in AE so that the footage can be swapped without having to re-render scenes in Maya.

There are advanced tutorials with complex scenes about render passes, but I've yet to find one the simple task of getting a 3D object with a screen composted in AE. So I followed these two tutorials by Marc Russo:

Creating a Luma Matte in Maya

https://vimeo.com/32740826

Importing Camera Data from AE into Maya

https://vimeo.com/32726702

The luma matte tutorial worked best in achieving the desired effect (sorta like this Action | VideoHive Templates | After Effects Project Files - YouTube), but in my self-test composite, the video while masked properly appears to be floating behind the matte -- not tracked with the geometry.

I am sure that a simple tutorial by one of you amazing pros would solve this.

This is a simple export out as a .ma file. The ASCII file is read natively inside of Maya. You would need to export out the luma matte as you say and apply a locator to the geometry to store the 3D translation geometry. Back in Malta I needed to do this to track a stupid toothfairy to apply pixie dust with Particular. Make sure you name the respectively "null_0" and so on based on which one. You might have to bake out the data on the locator as well. I onestly can't remember but it will work.