I'd also like to point out her use of tissue as an armature. She doesn't show this and only mentions it very briefly (see it removed in part 2). . In order to create the hollow head needed to string a BJD, the clay must wrap around a removable core. Just about anything "disposable" can be used, as long as it doesn't stick to clay. Artists will often wrap tissue, newspaper, Styrofoam, etc, with plastic wrap for their core.
In the 2nd video she shows how to cut the head apart to remove armature, clean up interior of head, cut out eyes, and generally make ready for finishing.. (The tiny skull at the end of Part 1 is made by JungaToy.)
*BJD=ball jointed doll