anchor.diff:      content.write("<body>");
       for (String r in _publicFileList.keys) {
         content.write("<div><a href=./${r}>${r}</a>");
  -      if(isMovieFile("${r}")) {
  +      if(isVideoFile("${r}")||isAudioFile("${r}")) {
           content.write("<a href=./${r}?preview=true>(preview)</a></div>");
         } else {
           content.write("</div>");        
  
positive.code:     StringBuffer content = new StringBuffer();
      content.write("<html>");
      content.write("<body>");
      content.write("<video src=\"${path}\" controls autoplay><p>unsupport video tag</p></video>");
      content.write("</body>");
      content.write("</html>");
  
  
negative.code:     });
    }
  
    bool isVideoFile(String path) {
      String type = contentType(path);
      if(type.startsWith("video/")){
        return true;
      } else {
        return false;
      }
    }
    //
    bool isAudioFile(String path) {
      String type = contentType(path);
      if(type.startsWith("audio/")){
        return true;
      } else {
        return false;
      }
    }
   
    Map<String,String> contentTypeMap = {".mp4":"video/mp4",
                                         ".ogv":"video/ogg",
                                         ".webm":"video/webm",
                                         ".m4v":"video/x-m4v",
                                         ".flv":"video/x-flv",
                                         ".wmv":"video/x-ms-wmv",
                                         ".ogg":"audio/ogg",
                                         ".oga":"audio/ogg",
                                         ".m4a":"audio/aac",
                                         ".mp3":"audio/mp3",
                                         ".midi":"audio/midi",
                                         ".mid":"audio/midi",
                                        };
    String contentType(String path) {
      int index = path.lastIndexOf(".");
      if(index <= 0) {
        return "application/octet-stream";
      }
      String suffix = path.substring(index);
      if(contentTypeMap.containsKey(suffix)) {
        return contentTypeMap[suffix];      
      } else {
        return "application/octet-stream";
      }
  