I'm a bit surprised that no one's mentioned a movie from 1947, "Carnegie Hall". No Mahler played in that one, but you did see and hear conductors Bruno Walter, Leopold Stokowski, Fritz Reiner, Artur Rodzinski, and Walter Damrosch. Also, there was cellist Gregor Piatigorsky, violinist Jascha Heifetz, plus singers Rise Stevens, Jan Peerce, Ezio Pinza, and Lily Pons. The story plot was insipid from the very start, but the film is valuable for seeing and hearing these big names in classical music at the time in action.
Wade