Thanks to Red for finding this. It's a trailer for the documentary about the bloody strike in Kentucky in 1973. I think it's up in parts on Youtube. A tv movie 'The Harlan County War' was made in 2000 with Holly Hunter on the same subject. Disputes in coal mines in America seem to be pretty violent. I suppose the most violent incident must be the Battle of Blair Mountain when US air force bombed their own citizens for the only time in history.