I'm not interested in paying for the online video course - does this article http://highexistence.com/the-wim-hof-method-revealed-how-to-... capture the gist of it? Does the book include anything else that's significant?

I was going to say the same thing. I don't know the veracity of the claims regarding ph levels but it's the one tool in my toolkit that consistently gives me an immediate positive return in my mental health. It'd be great if this is something that has far reaching clinical effects.

You can easily see ph levels go up to 7.5+ after each breathering session.

For reference: https://en.m.wikipedia.org/wiki/Wim_Hof