Mike, thanks for posting that. Brings back some memories. I arrived in Boston (Cambridge) in the fall of 1963 for my freshman year in college. Charles Munch had just ended his tenure as music director of the Boston Symphony (BSO), and Erich Leinsdorf had taken over. However, Munch would still come back to guest conduct. I was fortunate in hearing him and the BSO around 1965 playing the Saint-Saens Organ Symphony which he had earlier recorded (IIRC in 1961) for RCA (LSC-2341 IIRC). One of the sonic blockbusters of the time.
Interesting that this 1956 film talks about stereo recordings (you can see the stereo microphone placements in the film) even though the first stereo records were not made until 1958. RCA did start recording stereo in 1954 and did release some of them on tape shortly after that (I have one old 2 track 7.5 ips recording of the Fiedler Gaite Parisienne (LSC-1817) which was recorded in 1954 - it is incomplete, since the 2 track tape couldn't hold the 40 minutes or so length of the entire recording). However the records had to wait until 1958.
Larry