Post by Daniel Pyle
There is additional evidence that the performance is from 1950. The flute player (who is only seen from the back) is playing a French-style silver flute, which was used in the BPO only after WWII. (You can see silver flutes in the 1945 film of Celibidache conducting them in "Egmont" Overture.) Before that the Berliners always had wooden German-style flutes (see the 1942 film of Furtwängler leading BPO in the Prelude to Act I of "Die Meistersinger".)
It is all very curious! In the Mozart clip, at about 1:13 where the camera is closer to BW, the lighting on him seems to be different - ie: brighter - to the previous back-of-the-orchestra shot. That means more than one camera set-up, as per the brief inserts of the orchestra members themselves.
Then at about 3:34 you get a back-of-the-stalls shot, showing the hall, the platform and the conductor, with the audience in the foreground. This is referred to in the book quoted above, so as it's the pre-war Philharmonie then it must be 1930.
The page from the book referred to above also refers at the top to the movie "Carnegie Hall". This is complete on YouTube and features BW in part of the "Mastersingers" Overture. If you slide the time-line thing along to about 40:30 you get a close-up of BW conducting to a pre-recorded playback track. This was filmed in 1946 and I must say he looks older in this clip than he does in what we are told is the 1950 film of the Mozart! ...
Incidentally, was he similarly conducting to a pre-recorded track in the Mozart as well? It's certainly a much cleaner-sounding audio than the 1931 "Oberon" and with all the different camera set-ups needing precise editing of the film, presumably the audio is from 1950. Like I said, all very curious, not to say confusing!