[extractors] Use new framework for existing embeds (#4307)

`Brightcove` is difficult to migrate because it's subclasses may depend
on the signature of the current functions. So it is left as-is for now

Note: Tests have not been migrated

yt_dlp/extractor/rutube.py

@@ -1,4 +1,3 @@
-import re
 import itertools
 
 from .common import InfoExtractor
@@ -94,6 +93,7 @@ class RutubeIE(RutubeBaseIE):
     IE_NAME = 'rutube'
     IE_DESC = 'Rutube videos'
     _VALID_URL = r'https?://rutube\.ru/(?:video|(?:play/)?embed)/(?P<id>[\da-z]{32})'
+    _EMBED_REGEX = [r'<iframe[^>]+?src=(["\'])(?P<url>(?:https?:)?//rutube\.ru/embed/[\da-z]{32}.*?)\1']
 
     _TESTS = [{
         'url': 'http://rutube.ru/video/3eac3b4561676c17df9132a9a1e62e3e/',
@@ -128,12 +128,6 @@ class RutubeIE(RutubeBaseIE):
     def suitable(cls, url):
         return False if RutubePlaylistIE.suitable(url) else super(RutubeIE, cls).suitable(url)
 
-    @staticmethod
-    def _extract_urls(webpage):
-        return [mobj.group('url') for mobj in re.finditer(
-            r'<iframe[^>]+?src=(["\'])(?P<url>(?:https?:)?//rutube\.ru/embed/[\da-z]{32}.*?)\1',
-            webpage)]
-
     def _real_extract(self, url):
         video_id = self._match_id(url)
         info = self._download_and_extract_info(video_id)