That is just cural/costal breathing. It is not a cure for a stutter. It is something you must do at all times in order to attain fluency, and the relapse rates are about as high as you'd expect. It can be a good *tool* for some stutterers. One of the guys in our discord server sings its praises. But he also will be the first to tell you he is still a stutterer. It's not an 'unlearning'.