Complex sentence: "Musin had an incredible system" Kreizberg recalled, where the student would conduct and Musin would play at the piano, criticizing; then the roles were reversed, and Musin would comment again.
Split into simpler sentences: Musin had an incredible system Kreizberg recalled. The student would conduct and Musin would play at the piano, criticizing; then the roles were reversed, and Musin would comment again.