It's more like blutac - it pulls grit and dirt out of the paint, as long as you've used lube, it doesn't affect the paintwork at all.
We use the bilt hamber clay. we have used autoglym too, and nothing wrong with either - the bilt hamber is better value in our experience.
IMHO it is not abrasive - it is sticky. its called "clay" - but I doubt it comes out of the ground. Proper lube is paramount ( isn't it always ) - and we use autoglym rapid detailer, but there are literally hundreds of different ones, from Dodo Juice to .... your favourite search engine will enlighten you..
It does not affect paint work at all - only removes all the little bits of grit and crud from it - in basic terms, the paint will feel new after being clayed.
And defo use the two bucket wash method - unless you do, you are not washing the car, you are trashing the paint
As well as you tube, you'll find a mass of useful information over on:-
www.detailingworld.co.uk
including at least two members off here !!