I don't think that the Jews "ran" Hollywood, either then or now, although thee were some influential Jewish producers and directors, both then and now. I saw a documentary on the History Channel a couple of years ago that said that because the movies were a new industry the Jews had more opportunity to get in and make themselves influential, without dealing with the level of discrimination they suffered in other industries and professions.
At any rate, the Hollywood of the 40's and 50's was run by men who were grateful for the opportunities America had given them, who were patriotic, and who were loyal to the United States, even if they didn't agree with everything. Quite a contrast with today, isn't it??!!??
In James Hirsen's book "Tales from the Left Coast", he said at least one of the movie big wigs of old made the stars put away their Marxist books, (if they wanted to work there.) And he went into detail on how Hollywood helped the war effort.