In the video he touches on several points crucial for a successful startup including believing in your idea when no one does. Paradoxically, unlike many startup founders (Yahoo, Google, Microsoft) who left schools to focus on their business, he chose the opposite course and left business to join graduate school at Stanford just when YouTube was taking off. If he departed because he never expected YouTube to be a runaway hit (a belief augmented by initial hiccups YouTube met with) or if it was genuinely the allure of academia that he couldn’t resist is anybody’s guess. Does he regret having left YouTube in haste?