You're exactly right. They paid the third founder $700,000 to go away after their Series A. Smart, but I actually didn't respect him leaving his friends out to dry and forcing them into awkward conversations with their investors. I guess that lesson is make sure your founding team is committed before you dole out the stock certificates :).
Just on their ideas alone they were able to raise a Series A round of $18.4 Million from A-list venture capitalists. I was blown away by that fundraising process. With a couple of handouts and some smooth talk from an obviously intelligent CEO, they were able to raise all that money. No product. No prototype. No mockups. Just ideas.