what is logic behind rebirth

I was listening to this video, from Bhante Vimalaramsi. He says that one meditator experienced his past live and he had some pscotherapy before this. How is that possible? Buddhist talk about mind stream which flows to another body when a body dies, well what is this mind stream? This is the conciousness right? Is that some kind of emf waves or similar to wave which science hasn't descovered yet?