Is it? I suspect most teachers try to support students, but they will also try to discourage unhelpful habits. I also discourage students from ridiculing self, students, teacher or the class in the classroom, which I strongly suspect is not uncommon. Digging through my memories of teachers I've had or watched. I cannot recall any instances--at least intentionally--of shaming students (name-calling, essentially). Her evidence, on this clip at least, is anecdotal.
Especially troubling is the implication that this is widespread, and encourages riling parents up to be antagonistic, rather than cooperative, with teachers. I post this in the hope that Americans not overreact and take away their teachers' ability to create a healthy classroom discipline. It's a hard job, as is. Please do not assume teachers are out to get your kids.
My mother was a teacher and I can only recall her personally going to bat for me once, intervening on my behalf when a teacher grabbed a story I was working on while waiting for the class to finish a test. She did so diplomatically. Please assume the best. If your kid's teacher is antagonistic, often just talking with the teacher may make a difference.