Video Reviews : ****Excellent***Good**Fair*Poor : <i> Recent releases, reviewed by Times critics.</i>

Movies

*** “Unnatural Causes.” New Star. $79.95.

Alfre Woodard and John Ritter earned Emmy nominations for their performances in this 1986 TV movie about a Veterans Administration worker and a former soldier battling the federal bureaucracy to show that many of the disabilities plaguing Vietnam veterans were caused by their exposure to Agent Orange. Written by John Sayles and directed by Lamont Johnson, the film effectively conveys its characters’ frustration and sense of betrayal by the government. But it suffers from lack of a clear-cut villain: The VA’s reasons for trying to quash an investigation are never spelled out, the Agent Orange manufacturers aren’t named and the government’s rationale for using the chemical defoliant in Vietnam is not challenged. New Star says that for every tape sold, it will donate $1 to the Vietnam Veterans of America’s Agent Orange fund.