I believe it works. To my understanding the boiling is to sterilize the milk killing all good or bad bacteria before the growing of good yogurt bacteria starts. The cooling after and keeping warm is to create proper temperature for good yogurt bacteria to grow in the milk. The added yogyurt has to be live bacteria yogurt. There are some sterilized yoyurt on the market and that will not work here as a seeding yogur, I think. Correct me if I'm wrong.