What is "ExportFormat.fxgType"? It's nowhere in my Help, so it's probably not defined.
You cannot set 'anything you like' as "Export Format", InDesign must support the format to begin with. You may be missing that.
I realize that I won't be able to use ExportFornat if something is not defined.
The reason I was trying it, is because I couldn't find anything in OMV, and see if I can stumble on to something if it is similar to what I know.
To be absolutely clear, InDesign has no support for FXG (Flash XML Graphics).