javierloredo - There is no audio in the files. Also, it is speed up. You don’t really want to download 4 hours of video, do you? 
Off to the bottom left is a series of buttons that tell you when he is using different brushes. For example, most of the time he uses the standard brush but occassionally he will use the pinch brush.
You can watch the shelf to check his Z Intensity and other such things.
There really aren’t too many interface items to keep track of here.
The goal is to watch how he develops form and at what resolution level he starts to put more detail in.
Notice how in the beginning, with the resolution fairly low he blocks in the basic shape of the ear and then with more resolution he goes in to define the Helix and Antihelix.
These are as much a sculpting lesson, though with a Sphere 3D, as they are a lesson in using ZBrush. 
Ryan