U.S. navigates complicated cast of opposition groups in search of partner to fight Islamic State – Part 1

Summary: Over the weekend, the al-Nusra Front seized a major weapons cache from U.S.-backed Syrian rebels -- a blow to Washington's effort to keep territory out of militant control. President Obama said the U.S. and its allies must tread carefully to find an ally among all of the different factions. Judy Woodruff takes a look at some of the major groups fighting in Syria.