I too am a bit confused. (a There should have been a They maybe) This was a video of some sort? or a written interview. Having those two together talking about SW should refine the search. I'm guessing shortly after RotJ, could it have been part of the Joseph Campbell interviews?

poking around found these video of Lucas talking on a variety of generic topics. not what your looking for but someone of you's might be interested: http://www.achievement.org/achievers/luc0/movies/ Full interview here: http://www.achievement.org/autodoc/page/luc0int-1
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