compat_urlparse,
 )
 from ..utils import (
+    encode_dict,
     ExtractorError,
     int_or_none,
     parse_duration,
             'mail': username,
             'password': password,
         }
-        # Convert to UTF-8 *before* urlencode because Python 2.x's urlencode
-        # chokes on unicode
-        login_form = dict((k.encode('utf-8'), v.encode('utf-8')) for k, v in login_form_strs.items())
-        login_data = compat_urllib_parse.urlencode(login_form).encode('utf-8')
+        login_data = compat_urllib_parse.urlencode(encode_dict(login_form_strs)).encode('utf-8')
         request = compat_urllib_request.Request(
             'https://secure.nicovideo.jp/secure/login', login_data)
         login_results = self._download_webpage(
         extension = xpath_text(video_info, './/movie_type')
         if not extension:
             extension = determine_ext(video_real_url)
-        video_format = extension.upper()
 
         thumbnail = (
             xpath_text(video_info, './/thumbnail_url') or
             'url': video_real_url,
             'title': title,
             'ext': extension,
-            'format': video_format,
+            'format_id': 'economy' if video_real_url.endswith('low') else 'normal',
             'thumbnail': thumbnail,
             'description': description,
             'uploader': uploader,