Szigeti/Arrau Beethoven odd moment

from the live performance (1944) of the first movement of the Sonata No. 1 in D Major by Beethoven. The spliced passage is a unique moment in the the whole set of the 10 Sonatas in the set performed by these two artists. I only can guess about what happened. What do you think? Perhaps someone knows....?

Видео Szigeti/Arrau Beethoven odd moment канала sneddley