The original poster asked how to find pinholes in neoprene waders - which means ones made entirely of neoprene I believe.
That alcohol method shown on the simms video may work for breathables - but has never worked on neoprene for me.
And the flashlight method doesn't work very well on them either from my experience.
The best way I've found - is to turn them inside out, and fill them with water. And that works fine for holes in feet or legs.
However, if your leaks are in the crotch area or higher - it gets pretty hard to fill them up that far with water, while keeping them suspended. They get quite heavy.
What I do in that case, is blow them up with a shop vac - and the hose put in the exhaust port. Then dab soapy water around the area where i think the leak is, and look for air bubbles.