SEOUL, June 21 -- Jolted by video footage showing one of their countrymen being held in Iraq by kidnappers threatening to behead him, hundreds of South Koreans joined candlelight vigils and prayer groups Monday while the government scrambled to negotiate the hostage's release. In the video, first broadcast Sunday by the Arabic satellite TV network al-Jazeera and rerun countless times here Monday, Kim Sun Il, 33, screamed for his life while his hooded, armed captors demanded that South Korea quit the international military coalition in Iraq. The video was released three days after the government had finalized plans to begin...