[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):
@@ -28,10 +34,12 @@ 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)
 
+        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
-        if smil is False:
                 webpage = self._download_webpage(url, video_id)
                 entries = [
                     self.url_result(compat_urlparse.urljoin(url, video_url), 'VideoLecturesNet')