In this case they did a bunch of mock-interviews with people who had been through the YC process and got other developers to review it. I think at the end of ev

In this case they did a bunch of mock-interviews with people who had been through the YC process and got other developers to review it. I think at the end of every such interaction they could have asked those people how they will describe the product in 2 lines. Then they can take those responses and build a solid, concise response. That response, presenting views of people who are not the developers/not so close to the product, would probably appeal more/make more sense to the interviewers since they in a similar position of seeing a new product.