To the list of outsiders piling into venture capital in Silicon Valley, add one more: Edgar Bronfman Jr., the former head of Warner Music and the man who sold off the family business, Seagram Co., to French conglomerate Vivendi SA. Bronfman, now a managing partner at New York-based private equity firm Accretive LLC, is starting a venture firm with veteran investor Daniel Leff. The new firm, Waverley Capital, aims to raise a debut fund of about $100 million, targeting media investments.