You are wasting everyone's time with this question.
Dzogchen is a Vajrayana system. The Guru is indispensable.
If you want transmission, you must get it from a Guru. Live.
Is it a waste of time to investigate the nature of transmission? What you're saying is that "that's how it is, that's the tradition". Actually, that is an answer too and if that's all then I'm fine with it.
I've participated in Dzogchen transmission both face to face and DC's webcast, but I don't think it is relevant.