With its stock sagging and its auctions business slowing, eBay (Nasdaq: EBAY) plans to put more emphasis on its fixed-price business. Can eBay take a bite out of Amazon.com (Nasdaq: AMZN) and compete on price in a world of Costcos (Nasdaq: COST) and Wal-Marts (NYSE: WMT)? Does Facebook's social network pose a serious business threat to eBay? In this installment of "Fool Video," Motley Fool contributor Tim Beyers gives his take.