beirut two weeks russia say critically injure leader tahrir al-sham militant group syria undated video publish wednesday purport show leader abu mohamad al-golani apparently good health video show golani lecture fighters play scenes militants battle report strike early month russian defence ministry spokesman say golani lose arm critical condition russia ally syrian president bashar al-assad previously call nusra front group sever tie al qaeda last year january re-branded lead force hayat tahrir al-sham alliance oppose syrian government jihadist group dominant faction northwestern rebel-held province idlib syrian militant group release video leader apparently uninjured