This messes up the learning process. A class is only 45 minutes long, and when a student talks the teacher must stop their lecture in order to punish the student. It is even inappropriate to talk a little in the lesson while the teacher is pulling up a video. This may seem unfair but talking still has the potential to somehow distract the students who are not working. Perhaps it takes their minds out of class mode and sets the tone for a distracted learning environment.