All the presets work, with stylus and mouse if you follow the guidelines. Watch the video again, maybe you are missing something. Also if you need more contents here you have
Creating a basic brush
Creating variants from another brushes (Watercolor brushes) with icon library.
Things related with brush rotation and drawing angle.
How we can make RGBA brushes with oil behavior. Understanding a bit Masked brush.
How to Create Animated Brushes. Random
Importing Brushes, not bundles (remember you need to have the brushtips loaded, but if the brush use the default Krita 4 resources you don’t have to do anything else. When you import the brush, is done.)
Concepts used in pencils. Scatter, Pattern, Fuzzy Dab or Stroke
Concepts used in Shading brushes. Scalable, Easy to change the texture, not detail oriented (this one can be discussed , Controllable with the roughness feature )
Adjust the pressure to your needs