Greg says you should only hire developers who are smart and get things done. Talent is a lot like real estate – even if you know what you need and what you are willing to give in exchange, the talent may not be available. With the people you may want to hire, the situation is similar, and you just have to keep an eye on them. Startups often start by hiring friends but that is very different from hiring strangers. When hiring friends or people you already have a relation with, you want to make their joining as easy as possible and reduce obstacles.
When hiring strangers, you have to attract people. Figure out your strengths, internal and external. Do you use cool technologies in your startup? Highlight that. Does the job offer perks, even if it's a cool location or flexible schedule? Mention that.
Greg runs Codility, which tests coders, administering short programming tests and checking whether solutions are rock solid. In addition to testing coding, Greg recommends a few other things to test. (Starting at 12:50 Greg goes into detail about testing coders and examining code.)
Ask the candidate to pitch you something difficult. Maybe an idea they have, or maybe their final thesis. If they are able to communicate, they are likelier able to work with others.
Estimation or market sizing questions where the candidate has to think aloud and arrive at a ballpark result, preferable within the right order of magnitude. Examples are questions like "how many international flights depart from Heathrow every day" or "how many liters/gallons of petrol are used in the US daily". In questions like this, hearing the candidates logic is more important than the answer itself.
Greg finishes off with a number of tips for recruiting and hiring that are worth watching.