USA Today:  “Starting with the grainy images first broadcast by Kamau and other pioneer citizen watchdogs — notably the 1991 beating of Rodney King in Los Angeles, shot by a nearby resident— the public surveillance of cops has exploded to potentially include anyone with a cellphone.  The videos are so ubiquitous that analysts and police debate whether they are serving the public interest — or undermining public trust in law enforcement and even putting officers’ lives in jeopardy