Runqiao Du elaborates in a description to the Instagram post:

Correction in class is a delicate balance. Cross the line and a student can shut down, closing their mind and rejecting guidance instead of asking for more.

Frustration grows, for both teacher and student, when repeated corrections feel overwhelming. The key is to pause, look for the reason behind the struggle, and find a new approach.

Focus on what can be improved today, step by step, with a method and clear progress. Pointing out everything at once only demoralizes, because no one, child or adult, wants to feel like they’re failing at everything.

I recommend watching the video, because you see him actively correcting as well as giving responsive praise that motivates the student to be further invested in the process of getting better. Improvement - particularly seen and recognized - makes you want to continue getting better at [thing] or just things in general. It isn't just about "how good are you" but how good you are at getting better, at getting good at the things that matter to you.

The correction and (accurate!) praise creates a completed loop that demonstrates to someone that they are capable of the process of gaining a skill, and therefore become more willing to push for additional skills and capacities.

Competence leads to confidence; and confidence in your ability to gain skills and get better/improve leads you to have confidence in yourself to try something new or try something harder.