Joshua John Russell talks about piping thinned fondant. Anyone know how to do this?

I have done it several times in taking classes. You thin fondant or gumpaste with water and put in decorating bag and pipe as you do b/c or r/i. I have his video on craftsy , but haven,t watched it yet.But again, the way i told you is how i have been taught. We used it like that on a high heel shoe class. hth

I forgot to say, i  have even piped roses with thinned  down fondant, or thinned down modeling chocolate.

Thanks, I will give it a try. Should I go for the consistency of bettercream or royal icing?

Let me know if his video is worth purchasing.