In the beginning of the talk, Rob points out that while building software and products has become a lot faster, talking to people and getting feedback from them has not. The importance of doing early customer development is thus only underlined.
Rob shares his learnings from his earlier startups. The key to getting good feedback is staying tuned to strong emotional signals. Look for both positive and negative emotions around the problem you want to solve - or whatever problem the other person talks about in relation to your interview - and explore them further.
You can't outsource customer development, says Rob. It needs to be done by the founder, especially in the early days, and this includes doing sales. If you get someone else in between yourself and the customers, you risk not getting the bad news and undiluted feedback from your customers. Also, early on in a startup's life a commission-based salesperson may not be a good idea at all, since they may derail you from your vision, not because they'd be bad at what they do but especially if they do their job well. Premature scaling is the #1 killer of early-stage startups, and hiring a salesperson too early is a symptom of this.
Rob's customer development "Mom test" is a great example of how to ask good questions: even if you asked your mom about, she would give you an honest answer. Watch the video for the whole story, learn the patterns of customer development, and why you should always have your top three customer development questions ready.