In the following video, Motley Fool financial analyst Matt Koppenheffer talks about the top two holdings in his own personal portfolio, Wal-Mart (WMT -0.06%) and Berkshire Hathaway (BRK.B -1.35%). He tells us why he thinks Wal-Mart's competitive moat is an enduring one and what he likes about the structure of giant Berkshire Hathaway.