Lots of research on the effects of mediation on physical body activity. Just go to google scholar and search for meditation.

I've practiced mediation of various varieties for many years and yes it does make for a healthier spiritual, emotional, thoughtful, and physical life when practiced in moderation. When taken to the extreme ... well I guess you may end up setting yourself in fire.

One of the simplest things to try to learn how to do is slow your heart rate during meditation. It doesn't require great spiritual capacity. Very experienced meditators can, within a hermetically sealed box, lower their blood pressure, heart rate, metabolism, oxygen uptake, and some other aspects of their physiology, and then signal when they need fresh air.

Yes, it is significant that the monk did not display involuntary movement after he was consumed by the fuel-driven fire. Perhaps he had arrived at a state of reduced biological activity. The fire enveloped him instantly and would have deprived him of further oxygen. I'm sure he suffered -- there could be no escape from brief but very severe pain.

It is very shocking footage, but it is also deeply perplexing, because, as you say, the monk seems to be completely poised whilst his body is being consumed by fire. (It is also a very sad fact that many Tibetan Buddhist monks have followed this example and self-immolated in protest at the treatment of Buddhism by the Chinese Communist Party.)

It has long been known that yogis are able to enter states of trance in which their metabolic functions are suppressed or even appear to cease and that they display total indifference to sensation. There are reports of yogis who were buried in containers for long periods of time and then regained consciousness when freed. The whole purpose of such disciplines is to sever the identification with the physical body, and the fact that a monk could retain such composure throughout that experience indicates that he might have been able to do that.

However I would think that such states would be very difficult to reach and would require considerable training and a predisposition to asceticism; I would think us modern urbanites, raised in comfy homes with the creature comforts of modern civilization, would be utterly inept.

When taken to the extreme ... well I guess you may end up setting yourself on fire. — Rich

The Vietnamese government was pushing anti-Buddhists policies in the favour of the Catholic minority in a buddhist majority state!(Ex; giving extra preference to Catholics for government services, demolition of their religious sites, forced conversions ) No amount of peaceful protests seemed to be working at that time.
The ONLY option left for them was, well to do a sort of shoutout to the world about the injustice happening there.And that's the reason why as you say, "When taken to the extreme ... well I guess you may end up setting yourself on fire." is a totally unfair AND disrespectful statement towards those monks.
I think you actually hadn't read about the issue in a depth, so I guess its an honest mistake.

But please.... please.... don't disrespect the sacrifice those monks did!

So you figure setting oneself on fire is going to change the views of the Vietnamese government? Sometimes reading history books is more helpful than meditation when it comes to government repression. But, if someone wants to set oneself on fire because of their meditation, then who am I to argue.

No. it is not going to change the views of the government.(atleast not of the corrupt officials). It was a last resort to the peaceful protests. You go further ahead and you are looking at mass riots, civil war, ethnic cleansing of minorities, in this case, christians.(See Myanmar).
I think the monks saw it and instead of any violence, they preferred to change the heart of the minorities(win them over) and the world at large.

AND the most simple fact is that they did it because they COULD! can you do it ?can I do it? No. Who are we to question the actions of a man who can stay poised when his skin is melting?
What do we know about the brain, mind or wisdom of such a person?

And now I am also curious to know your views about euthanasia?

Each person can do what they want with their own body.

Strange isn't it? The number 1, on average, is an impotent quantity. It takes many to make a difference in this world. Yet, an exceptional 1, like this monk, can do, in an instant, what many take years to achieve. Completely irrelevant...just a thought.

My take on meditation is that it reminds me of our reptilian ancestors and hibernation. A very simple and naturalistic explanation is that the brain can be shut down through meditative practice, just as lizards naturally do. Nothing really fascinating in this.