This guy is talking about building mockups, and only mockups.
A prototype is a working version of all key features that can be used as if it were the final product albeit in a somewhat limited fashion (E.g. the edges aren't rounded)
A mockup demonstrates the value in a non-working fashion so people can respond to the general idea.
If you don't get mockup vs prototype right, it's pretty hard for me to value your opinion on these matters.
This guy is talking about building mockups, and only mockups.
A prototype is a working version of all key features that can be used as if it were the final product albeit in a somewhat limited fashion (E.g. the edges aren't rounded)
A mockup demonstrates the value in a non-working fashion so people can respond to the general idea.
If you don't get mockup vs prototype right, it's pretty hard for me to value your opinion on these matters.