As a founder I
loved to get feedback like this. Was I proud of some feature or design that I'd worked hard on? That's nice, but if it's not working for customers, it's not working. Swallow pride, move on.
Although that's a healthy attitude, it gets tricky when the company grows and the customer is criticizing work done by your employees. Your instinct is still that the customer is automatically right, and that's still true, but you have to be less blunt with employees than you'd be with yourself. You need to acknowledge their work was good, we just need to try something different. Regardless, they need to hear and act on it. And there is no way you call a customer a "prick", for offering polite feedback like in that video. You thank them.
Sometimes I'd remind folks that it wasn't me, it was our customers who were paying for our salaries, the office around us, the chairs we're sitting on. Ultimately the customers are the boss, not me.
Edit: If you have investors, now you have two bosses.