What is this Silent Second Mortgage Fraud?

[Richard Villandry]

Hey BP!

If i have a private investor that is willing to lend me a down payment on a property how do you structure it to not consider it a silent second fraud? For instance, if a friend gave me 20,000 for a down payment and we both agreed he would get 6% for 5 yrs and then at 5yrs he would get the 20,000 back, is this considered silent second? Please help with a better understanding so i don't get myself in trouble.

Thanks Everyone!