I stopped watching when the "presenter" twice referred to the emitter of a BJT as the "negative lead". He's using the mutual inductance of two surface mount inductors as a transformer. It's certain to be less efficient than designs where the magnetic fields are coupled through a traditional ferrite but since the joule thief is so forgiving of such variations, it still works. He stated an interest in miniaturization but didn't take it to the next level, replacing the transistor and resistor with SMD components also.