The shout encourages and facilitates the forceful and complete exhalation of air. So this is simply the application of the principles of proper breathing in action. In Seido karate and Seido meditation, therefore, the principles underlying the importance and role of the breath are the same. The mechanics of some breathing techniques are slightly different, but they arise largely from the sitting zazen versus moving meditation. As with all phases of karate, experience is the key to understanding.
Experience is gained through individual practice.
An experienced teacher and the environment of a dojo are important in creating the atmosphere for serious study and for giving students the proper grounding so they will not develop bad habits. If you want to learn how to breathe, just sit.