In “Death of a Shaman,” filmmaker Fahm Fong Saeyang traces the American “nightmare” of her immigrant father, a respected “spirit priest” in Southeast Asia's Mien community who was sucked into a life of poverty and drug abuse after fleeing the chaos of Laos in the late 1970s. Then Yoon died in an accident in 2000. But he left behind his videocam and a wealth of tapes. He also left behind a daughter on a redemptive mission.