code: function addOkListener(){
          dialog.onok = function(){
              $G("preview").innerHTML = "";
              var currentTab =  findFocus("tabHeads","tabSrc");
              switch(currentTab){
                  case "video":
                      return insertSingle();
                      break;
                  case "videoSearch":
                      return insertSearch("searchList");
                      break;
                  case "upload":
                      return insertUpload();
                      break;
              }
          };
          dialog.oncancel = function(){
              $G("preview").innerHTML = "";
          };
      }
docs: 监听确认和取消两个按钮事件，用户执行插入或者清空正在播放的视频实例操作