diff --git a/youtube_dl/extractor/abcnews.py b/youtube_dl/extractor/abcnews.py
index 01247fead..6ae5d9a96 100644
--- a/youtube_dl/extractor/abcnews.py
+++ b/youtube_dl/extractor/abcnews.py
@@ -49,7 +49,7 @@ def _real_extract(self, url):
 
 class AbcNewsIE(InfoExtractor):
     IE_NAME = 'abcnews'
-    _VALID_URL = 'https?://abcnews\.go\.com/(?:[^/]+/)+(?P<display_id>[0-9a-z-]+)/story\?id=(?P<id>\d+)'
+    _VALID_URL = r'https?://abcnews\.go\.com/(?:[^/]+/)+(?P<display_id>[0-9a-z-]+)/story\?id=(?P<id>\d+)'
 
     _TESTS = [{
         'url': 'http://abcnews.go.com/Blotter/News/dramatic-video-rare-death-job-america/story?id=10498713#.UIhwosWHLjY',
diff --git a/youtube_dl/extractor/ard.py b/youtube_dl/extractor/ard.py
index 07e67dd33..3a806a69b 100644
--- a/youtube_dl/extractor/ard.py
+++ b/youtube_dl/extractor/ard.py
@@ -238,7 +238,7 @@ def _real_extract(self, url):
 
 
 class ARDIE(InfoExtractor):
-    _VALID_URL = '(?P<mainurl>https?://(www\.)?daserste\.de/[^?#]+/videos/(?P<display_id>[^/?#]+)-(?P<id>[0-9]+))\.html'
+    _VALID_URL = r'(?P<mainurl>https?://(www\.)?daserste\.de/[^?#]+/videos/(?P<display_id>[^/?#]+)-(?P<id>[0-9]+))\.html'
     _TEST = {
         'url': 'http://www.daserste.de/information/reportage-dokumentation/dokus/videos/die-story-im-ersten-mission-unter-falscher-flagge-100.html',
         'md5': 'd216c3a86493f9322545e045ddc3eb35',
diff --git a/youtube_dl/extractor/globo.py b/youtube_dl/extractor/globo.py
index dbacbfc61..5638be48f 100644
--- a/youtube_dl/extractor/globo.py
+++ b/youtube_dl/extractor/globo.py
@@ -19,7 +19,7 @@
 
 
 class GloboIE(InfoExtractor):
-    _VALID_URL = '(?:globo:|https?://.+?\.globo\.com/(?:[^/]+/)*(?:v/(?:[^/]+/)?|videos/))(?P<id>\d{7,})'
+    _VALID_URL = r'(?:globo:|https?://.+?\.globo\.com/(?:[^/]+/)*(?:v/(?:[^/]+/)?|videos/))(?P<id>\d{7,})'
 
     _API_URL_TEMPLATE = 'http://api.globovideos.com/videos/%s/playlist'
     _SECURITY_URL_TEMPLATE = 'http://security.video.globo.com/videos/%s/hash?player=flash&version=17.0.0.132&resource_id=%s'
@@ -396,7 +396,7 @@ def _real_extract(self, url):
 
 
 class GloboArticleIE(InfoExtractor):
-    _VALID_URL = 'https?://.+?\.globo\.com/(?:[^/]+/)*(?P<id>[^/]+)(?:\.html)?'
+    _VALID_URL = r'https?://.+?\.globo\.com/(?:[^/]+/)*(?P<id>[^/]+)(?:\.html)?'
 
     _VIDEOID_REGEXES = [
         r'\bdata-video-id=["\'](\d{7,})',
diff --git a/youtube_dl/extractor/onet.py b/youtube_dl/extractor/onet.py
index fc22ad5eb..9cbc7c2e2 100644
--- a/youtube_dl/extractor/onet.py
+++ b/youtube_dl/extractor/onet.py
@@ -90,7 +90,7 @@ def _extract_from_id(self, video_id, webpage):
 
 
 class OnetIE(OnetBaseIE):
-    _VALID_URL = 'https?://(?:www\.)?onet\.tv/[a-z]/[a-z]+/(?P<display_id>[0-9a-z-]+)/(?P<id>[0-9a-z]+)'
+    _VALID_URL = r'https?://(?:www\.)?onet\.tv/[a-z]/[a-z]+/(?P<display_id>[0-9a-z-]+)/(?P<id>[0-9a-z]+)'
     IE_NAME = 'onet.tv'
 
     _TEST = {
diff --git a/youtube_dl/extractor/rutube.py b/youtube_dl/extractor/rutube.py
index 9ca4ae147..5d0ace5bf 100644
--- a/youtube_dl/extractor/rutube.py
+++ b/youtube_dl/extractor/rutube.py
@@ -88,7 +88,7 @@ def _real_extract(self, url):
 class RutubeEmbedIE(InfoExtractor):
     IE_NAME = 'rutube:embed'
     IE_DESC = 'Rutube embedded videos'
-    _VALID_URL = 'https?://rutube\.ru/(?:video|play)/embed/(?P<id>[0-9]+)'
+    _VALID_URL = r'https?://rutube\.ru/(?:video|play)/embed/(?P<id>[0-9]+)'
 
     _TESTS = [{
         'url': 'http://rutube.ru/video/embed/6722881?vk_puid37=&vk_puid38=',
diff --git a/youtube_dl/extractor/spiegel.py b/youtube_dl/extractor/spiegel.py
index 3c552807e..74cb3a08a 100644
--- a/youtube_dl/extractor/spiegel.py
+++ b/youtube_dl/extractor/spiegel.py
@@ -103,7 +103,7 @@ def _real_extract(self, url):
 
 
 class SpiegelArticleIE(InfoExtractor):
-    _VALID_URL = 'https?://www\.spiegel\.de/(?!video/)[^?#]*?-(?P<id>[0-9]+)\.html'
+    _VALID_URL = r'https?://www\.spiegel\.de/(?!video/)[^?#]*?-(?P<id>[0-9]+)\.html'
     IE_NAME = 'Spiegel:Article'
     IE_DESC = 'Articles on spiegel.de'
     _TESTS = [{
diff --git a/youtube_dl/extractor/twitter.py b/youtube_dl/extractor/twitter.py
index b73842986..c5a5843b6 100644
--- a/youtube_dl/extractor/twitter.py
+++ b/youtube_dl/extractor/twitter.py
@@ -342,7 +342,7 @@ def _real_extract(self, url):
 
 class TwitterAmplifyIE(TwitterBaseIE):
     IE_NAME = 'twitter:amplify'
-    _VALID_URL = 'https?://amp\.twimg\.com/v/(?P<id>[0-9a-f\-]{36})'
+    _VALID_URL = r'https?://amp\.twimg\.com/v/(?P<id>[0-9a-f\-]{36})'
 
     _TEST = {
         'url': 'https://amp.twimg.com/v/0ba0c3c7-0af3-4c0a-bed5-7efd1ffa2951',
diff --git a/youtube_dl/extractor/youtube.py b/youtube_dl/extractor/youtube.py
index 8fc26bd02..5082cb589 100644
--- a/youtube_dl/extractor/youtube.py
+++ b/youtube_dl/extractor/youtube.py
@@ -2417,7 +2417,7 @@ class YoutubeSubscriptionsIE(YoutubeFeedsInfoExtractor):
 
 class YoutubeHistoryIE(YoutubeFeedsInfoExtractor):
     IE_DESC = 'Youtube watch history, ":ythistory" for short (requires authentication)'
-    _VALID_URL = 'https?://www\.youtube\.com/feed/history|:ythistory'
+    _VALID_URL = r'https?://www\.youtube\.com/feed/history|:ythistory'
     _FEED_NAME = 'history'
     _PLAYLIST_TITLE = 'Youtube History'