The amount of that stuff you'll go through would be more than using a regular car wash. He is using a micro fiber towel but notice he sprays a heavy amount on one spot of the car, I think that bottle is only 16 oz. in the first place. Detailer I use only lasts me a couple of times and I don't use that very often.
I was considering using something like this for my slightly dirty/dusty cars. Nothing too bad. They sell a gallon of the Freedom for $40. It should last quite a while for touch ups. Why would this cause more scratching than detailers?