I'm a 22 y/o cellist, this piece was my semester final last week. I've been playing cello for 3 years and i have tonsay, I'M COMPLETELY IMPRESSED with this kid's wonderful playing, one can tell that they'll be one of the great cellists some day. I don't even care that their already better than me, it's just to beautiful to see them play that good, it makes me so happy :') congrats! And congrats to that great teacher, she reminds me of my own teacher.
Does he still play? Know many kids who start so strong but burn out, especially when the fumes hit them (gas fumes from their car and perfume from the girls). But he seemed very engaged and willing to do the work so maybe he is near mastery.
One thing I don‘t understand about these lessons: have the students memorized the music? I used to have sheet music in front of me in every (violin) lesson.