This depends on the tools you are using and the format you want to export. The tutorial is using dx7 compatible 3ds. that allows scale/move/rotate animations only. It doesn't matter if the leg is made of 2 boxes, or if you have modelled lower leg and upper leg as realistic highpoly models. The Pivots don't care about that, simply position them where they need to be. This Format requires every animatable part to be an individual mesh in the hierarchical structure (foot is child of lower leg, lower leg is child of upper leg, upper leg is child of waist...) the hierarchical linking is done from outside to the center, where the chest is usually the top parent.
The other format, B3D is capable of mesh deformation. You would create your model as one singe mesh, then add the bones to it, assign every vertex to one or more bones.
Then you can follow the same steps to animate it, simply use the bones instead of the pivots. There are some problems with joints, you have to prevent "folding" problems, so eg. a knee should be made of 3 bones, not only one.
The other format, B3D is capable of mesh deformation. You would create your model as one singe mesh, then add the bones to it, assign every vertex to one or more bones.
Then you can follow the same steps to animate it, simply use the bones instead of the pivots. There are some problems with joints, you have to prevent "folding" problems, so eg. a knee should be made of 3 bones, not only one.