I think I have an explanation for NDE and the replay of memories.
When nearing a natural death, the oxygens levels to the brain deplete dramatically, this is known to make the subject lapse in and out of consciousness. This in turn induces a fuzzy reality type state, which is neither fully awake or fully asleep. Many of us, have also have experienced a smaller-scale version of in this in lucid dreams. In lucid dreams, the divide between reality and imagination becomes blurred, giving the illusion, that our imagination/dream is real, and is really taking place.
I have had such dreams myself, where I've physically felt, I've floated out of my body. The experience was vivid and felt, perhaps liberating, yet at the same time terrifying. I was consciously aware that it was a dream; my fear was my paralysis - inability to animate my limbs or breathe properly, and break out of my dream. Sometimes it felt, as if I'd never wake up again. With every ounce of energy in my body, and extreme determination, I managed to open my eyes and see the surroundings of my bedroom, yet struggling with some unknown force, that was attempting to pull me back in; and it did pull me back in, and I tried to fight it, for what seemed like an eternity of struggle, lapsing in and out of my dream repeatedly. Eventually, and perhaps the fear of death is one factor that empowered me, I would fire on every cylinder, and shoot up upright, sometimes lunging myself of my bed.... It was always a dream.
Now try and realise this. I was not near death. Yet, these people who experiece NDE; are. They do not have energy, or the determination, to lapse out of their state, and in addition to that, they suffer severe oxygen depletion. This cause many neural pathways in the brain to break, in other words your state of mind is in a frenzy: memories, thoughts, ideas, fears, randomly fluctuating erratically, creating this bizzarre, but, surreal reality.
Now the following comes into play:
1: Memories replaying back to them
2: Preconcieved notions of death projected in front of them
3: The physical feeling of leaving the body
We can see, that this may indeed be the case, by analysing common traits of NDE: The experience is always culture specific: some see Jesus; some see Buddha; some see God; some see their relatives; some see hell. Therefore, their experience is always moulded on their belief systems.
Secondly, this only happens in natural/nearing death situations, in particular, with depleting oxygen levels. It does not happen in unnatural/instant death situations; such as dying from falling, being shot dead, shocked, poísoned, cardiac arrest etc.
Thus by a process of logic, it becomes quite clear, that NDE is not real, as in a touch and go with after life, and is basically a natural biological side-effect of the dying brain.
Non-death OBE is also a similar mechanism. Not exactly a dying brain, but a brain with depleted levels of oxygen, or under the influence of hallucinogenic compounds. In fact, most of the time I had OBE-like experiences, I also found it difficult to breathe.