[youtube] Fix missing format details for 60fps DASH formats

60fps DASH formats do not appear in the DASH manifest, but the non-DASH
video info page does contain additional parameters for DASH formats that
we can parse.

Use those when they exist.

This fixes "bestvideo" not selecting 60fps formats over similar 30fps
formats just because the file size is unknown.

youtube_dl/extractor/youtube.py

@@ -1243,7 +1243,7 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
             encoded_url_map = video_info.get('url_encoded_fmt_stream_map', [''])[0] + ',' + video_info.get('adaptive_fmts', [''])[0]
             if 'rtmpe%3Dyes' in encoded_url_map:
                 raise ExtractorError('rtmpe downloads are not supported, see https://github.com/rg3/youtube-dl/issues/343 for more information.', expected=True)
-            url_map = {}
+            formats = []
             for url_data_str in encoded_url_map.split(','):
                 url_data = compat_parse_qs(url_data_str)
                 if 'itag' not in url_data or 'url' not in url_data:
@@ -1303,8 +1303,33 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
                     url += '&signature=' + signature
                 if 'ratebypass' not in url:
                     url += '&ratebypass=yes'
-                url_map[format_id] = url
+
-            formats = _map_to_format_list(url_map)
+                width = None
+                height = None
+                size_str = url_data.get('size', [''])[0]
+                if size_str.count('x') == 1:
+                    width, height = [int_or_none(x) for x in size_str.split('x')]
+
+                format_url = {
+                    'format_id': format_id,
+                    'url': url,
+                    'player_url': player_url,
+                    # As of this writing these are only defined for DASH formats:
+                    'filesize': int_or_none(url_data.get('clen', [None])[0]),
+                    'tbr': float_or_none(url_data.get('bitrate', [None])[0], scale=1024),
+                    'width': width,
+                    'height': height,
+                    'fps': int_or_none(url_data.get('fps', [None])[0]),
+                }
+
+                # drop Nones so they do not overwrite the defaults from self._formats
+                format_url = dict((k, v) for k, v in format_url.items() if v is not None)
+
+                format_full = self._formats.get(format_id, {}).copy()
+                format_full.update(format_url)
+
+                formats.append(format_full)
+
         elif video_info.get('hlsvp'):
             manifest_url = video_info['hlsvp'][0]
             url_map = self._extract_from_m3u8(manifest_url, video_id)