This is more a prelim video about breathing exercises in Yoga which also covers the anatomy and physiology of respiratory muscles. There are three sets of muscles involved in breathing. The intercostal muscles raise and lower the ribs like the handle of a bucket. The accessory respiratory muscles are also involved in other kinds of movement and are at the top of the chest and sort of there for emergencies to maximise lung capacity. Finally, the diaphragm is the most efficient muscle for breathing and at rest is surprisingly high - just below the nipples.
Many people breathe inefficiently, using their intercostals and accessory muscles more than their diaphragm. When they do this, they are expending a lot of effort on respiration without maximising their vital capacity (see the lung volumes video here):
This is important because, whereas a single breath taken inefficiently is not going to cost you much energy, a long series of respiratory actions of this kind is going to add up to a lot of wasted effort for a relatively small benefit. As a result, if you breathe inefficiently, you are probably going to get needlessly tired.
Inefficient breathing is also addictive. If you train yourself to breathe better, it will at first feel that you are almost suffocating and you will experience an urge to fill your lungs using the less efficient muscles and the cycle will continue, making you completely knackered. However, if you persist with the habit described in the first video, you will lose that urge and go on to breathe better with less exhaustion.
Now, i am a little aware of the irony of including a video on teaching people to breathe when it's the classic example used by home edders to illustrate the silliness of schooling! I would answer that by saying that the stresses and strains of everyday life lead people to breathe poorly, even though they can do it fine soon after birth.