4)open iFile var/mobile/application/(FIND THE INSTAGRAM FOLDER) / library /application support / instagram/ videos??? You will see either two files there (.MOV&.MOV.locked) they have the same filenames so do not be confused??? or files with filenames (.buffer&.MOV???s with 0bytes) delete everything except the two important files with the same filenames with formats-(.MOV&.MOV.locked)