Ugh... This is so unscientific. Not least because it says:
When your heart stops beating, there is no blood getting to your brain. And so what happens is that within about 10 sec., brain activity ceases —as you would imagine.
That's so not true. Brain death takes an entire five minutes after the heart stops beating. This is because oxygen doesn't disappear when the heart stops beating, just new supplies of it. People lose consciousness within 10 seconds; brain activity continues for far longer than that.
What happens is, as other people have suggested, the brain goes into a panicked state to conserve energy - shutting down unessential areas. The brain releases an enormous BURST of endorphins and other chemicals (the feeling of euphoria), while other areas relating to vision begin to fire spontaneously, giving the idea of a bright light (it's not heaven: it's your brain dying).
I'm not a Jesus freak, but I'm quite sure that when we die, we don't just vanish. Remember the law of conservation of energy... Energy cant be created or destroyed - only transformed.... where does our energy go? Just into thin air? Dissipated as heat? I think not.
What do you think energy is? Kinetic energy, chemical energy... The "energy" of your body doesn't disappear at all. You need to understand that your brain and body are chemical machines: your consciousness HAS no energy of its own; your mind is the product of the chemicals and matter in your brain. They become water, part of someone else's arm, air, soil etc.
No energy or information is lost - but your consciousness ceases to exist, as the matter is no longer arranged in a way to make it exist.
(If I smashed up my computer - the metal parts would still exist in some form somewhere, but it'd be delusional to think my Windows7 operating system was still functioning in full and "floating around" somewhere...)