[videolecturesnet] Improve playlist extraction

youtube_dl/extractor/videolecturesnet.py

@@ -3,8 +3,14 @@ from __future__ import unicode_literals
 import re
 
 from .common import InfoExtractor
-from ..compat import compat_urlparse
-from ..utils import parse_duration
+from ..compat import (
+    compat_HTTPError,
+    compat_urlparse,
+)
+from ..utils import (
+    ExtractorError,
+    parse_duration,
+)
 
 
 class VideoLecturesNetIE(InfoExtractor):
@@ -28,17 +34,19 @@ class VideoLecturesNetIE(InfoExtractor):
         video_id = self._match_id(url)
 
         smil_url = 'http://videolectures.net/%s/video/1/smil.xml' % video_id
-        smil = self._download_smil(smil_url, video_id, fatal=False)
-
-        # Probably a playlist
-        if smil is False:
-            webpage = self._download_webpage(url, video_id)
-            entries = [
-                self.url_result(compat_urlparse.urljoin(url, video_url), 'VideoLecturesNet')
-                for _, video_url in re.findall(r'<a[^>]+href=(["\'])(.+?)\1[^>]+id=["\']lec=\d+', webpage)]
-            playlist_title = self._html_search_meta('title', webpage, 'title', fatal=True)
-            playlist_description = self._html_search_meta('description', webpage, 'description')
-            return self.playlist_result(entries, video_id, playlist_title, playlist_description)
+
+        try:
+            smil = self._download_smil(smil_url, video_id)
+        except ExtractorError as e:
+            if isinstance(e.cause, compat_HTTPError) and e.cause.code == 404:
+                # Probably a playlist
+                webpage = self._download_webpage(url, video_id)
+                entries = [
+                    self.url_result(compat_urlparse.urljoin(url, video_url), 'VideoLecturesNet')
+                    for _, video_url in re.findall(r'<a[^>]+href=(["\'])(.+?)\1[^>]+id=["\']lec=\d+', webpage)]
+                playlist_title = self._html_search_meta('title', webpage, 'title', fatal=True)
+                playlist_description = self._html_search_meta('description', webpage, 'description')
+                return self.playlist_result(entries, video_id, playlist_title, playlist_description)
 
         info = self._parse_smil(smil, smil_url, video_id)