If it's available where you live... part one of Neil Brand's 3-part doc on the history of film music is available on BBC iPlayer...

http://www.bbc.co.uk/iplayer/episode/b03b45h4/sound-of-cinema-the-music-that-made-the-movies-1-the-big-score

This part covered big orchestral scores, so naturally it touches on the influence of Star Wars and in turn Korngold's influence on it. Well worth a watch. I didn't remember seeing the footage of JW conducting along to the B&W workprint of ESB but I probably have seen it somewhere before in the dim past.