He reported on patients who had clinically died and were revived. They were able repeat exactly the conversations tat was had in the room (while they were dead). Make of that what you will
There's a fundamental difference between being 'clinically dead', no heartbeat, no pulse, and being 'brain dead'. The brain continues to function for a wee while after heartbeat and pulse stops. This is a quirk of physiology and nothing whatsoever to do with a 'conscience' or a 'spirit'. It's why doctors can stop your heart and restart it without you killing you, because provided the brain is still receiving oxygen brain function carries on and you are not in any danger of dying.
What point he thinks he's making is beyond me, because it stands to reason that if your brain is functional you will have some cognitive ability even while on the operating table. You don't 'die' when you go to sleep every night. You are still capable of hearing conversations being conducted in the same room, but in most cases you don't recall them because your brain is in a sleep state. Sometimes you will, or they will be sufficient to prompt your brain to wake you from a sleep state.
Nothing this doctor is reporting is in any way a revelation, and it does not suggest anything at all about 'the conscience never dying'. It reads very much like yet another believer attributing something to 'woo' purely because it marries with their belief, but in reality it's a nonsense. As a doctor you'd assume he believes in science, yet the way you've reported it, it seems that here he is attributing a known physiological phenomenon, that is not even unique to humans, to some sort of ill-defined 'conscience' or 'spirit', when it's nothing more than well understood and documented biology and chemistry. That's not a doctor I'd want anywhere near any human being I cared about.