"It sort of filtered into their subconscious through motion pictures, but it's an historical secret. This - whatever this is - needs to be studied and, in a kind of definitive way, talked about"

This quote by Dwight Schultz suggests that there is an important historical trick that has actually been passed down through generations, but not in a conscious method. Rather, it has actually been soaked up through motion pictures, which suggests that it is a story or narrative that has been informed through movie. He believes that this secret needs to be studied and talked about in a definitive method, which suggests that it is important to understand the history and implications of this trick in order to totally understand its significance. This quote suggests that there is a hidden history that requires to be uncovered and talked about in order to acquire a much better understanding of the past and its implications for today.