Last week, I invited Fool co-founder David Gardner into our brand-new Motley Fool studio space here in Alexandria, Va. We spent nearly an hour talking about the state of the retail investor here in 2013, his investing philosophy, and his current thinking on a half-dozen specific stocks in his Supernova universe. (You can view the entire interview here.)

One of the stocks we discussed was Facebook (NASDAQ:FB). In late November, David tweeted: "I am confident that #Facebook beats the market from here, next 5 years. #markthisdown."

I asked David what makes him bullish on Facebook -- which is, in its current form, a display-ad business model. You can watch his answer in the video below (run time: 5:29). Spoiler: It boils down to visionary management and a first-mover advantage in an important industry.