I'm a bit skeptical in that she uses soap as part of the "carrier medium" (mixed with the glaze). Having used detergent in the past to modify paint consistency, I'd worry that it might remain soluble and rub off, or you'd have to apply a strong varnish on top.
That said, it might look absolutely superb for creating lava effects on larger surfaces, especially if you could apply various shades or use a polyshade paint in the appropriate colours.