Ed Baker on FB and Uber's North Star metric

This is a cool video for any growth hackers/product folks. 'Wishing your friend happy birthday on Facebook was a feature introduced by the growth team to increase DAU'! http://growthhackers.com/videos/how-facebook-uber-used-a-north-star-metric-to-drive-growth cc:@GrowthHackers

It seems obvious in hindsight, but such an interesting way to get people to get onto an app.