[plutotv] Fix extractor for URLs with `/en`

Closes #431

yt_dlp/extractor/plutotv.py

@@ -19,7 +19,16 @@ from ..utils import (
 
 
 class PlutoTVIE(InfoExtractor):
-    _VALID_URL = r'https?://(?:www\.)?pluto\.tv(?:/en)?/on-demand/(?P<video_type>movies|series)/(?P<slug>.*)/?$'
+    _VALID_URL = r'''(?x)
+        https?://(?:www\.)?pluto\.tv(?:/en)?/on-demand
+        /(?P<video_type>movies|series)
+        /(?P<series_or_movie_slug>[^/]+)
+        (?:
+            /seasons?/(?P<season_no>\d+)
+            (?:/episode/(?P<episode_slug>[^/]+))?
+        )?
+        /?(?:$|[#?])'''
+
     _INFO_URL = 'https://service-vod.clusters.pluto.tv/v3/vod/slugs/'
     _INFO_QUERY_PARAMS = {
         'appName': 'web',
@@ -146,17 +155,13 @@ class PlutoTVIE(InfoExtractor):
         return info
 
     def _real_extract(self, url):
-        path = compat_urlparse.urlparse(url).path
-        path_components = path.split('/')
-        video_type = path_components[2]
-        info_slug = path_components[3]
-        video_json = self._download_json(self._INFO_URL + info_slug, info_slug,
-                                         query=self._INFO_QUERY_PARAMS)
+        mobj = self._match_valid_url(url).groupdict()
+        info_slug = mobj['series_or_movie_slug']
+        video_json = self._download_json(self._INFO_URL + info_slug, info_slug, query=self._INFO_QUERY_PARAMS)
 
-        if video_type == 'series':
+        if mobj['video_type'] == 'series':
             series_name = video_json.get('name', info_slug)
-            season_number = int_or_none(try_get(path_components, lambda x: x[5]))
-            episode_slug = try_get(path_components, lambda x: x[7])
+            season_number, episode_slug = mobj.get('season_number'), mobj.get('episode_slug')
 
             videos = []
             for season in video_json['seasons']: