I bought it a few years ago, and read it and profited from it.
The main thing thing I learned, was that there are two physical spasms to an orgasm: the internal prostate one, and penile one. Usually, we guys have them both so close together we're not aware they can be separated. But they can. That's where the multiple part starts to come in. If you're 'edging', and stop the stimulation at the right point, you'll get the prostate orgasm, and a little squirt of fluid. Very pleasant sensation. BUT YOU'RE STILL HORNY. YOU DON'T HAVE THE 'LETDOWN' UNTIL YOU HAVE THE PENILE ORGASM. You can do the internal one again; another pleasant sensation, and another little squirt. And your dick is still staying hard, by the way. Then go for the penile one, and you shoot what is left, feel good, and your dick deflates.
I've done this lots, but it's a masturbation and porn thing for me. I don't have a partner for that, and somehow I think it would be a very selfish sex act. One of those 'you look after me today, and I'll do it for you tomorrow' things.
As an aside to this, one reason I like to do this sometimes, (and I don't always), is that I like to eat my own sperm sometimes. But when I'm interested is when I'm horny, not after I've just cum when I'm having the letdown. This gives a squirt to lick up while I'm still horny. So I can look at a picture of a creampie or a girl with a facial, and imagine licking up the jizz, and actually have some to taste. To each his own; this isn't really a place to be bashful
I don't think it would be helpful or appropriate for C's gentleman callers.
O.