[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/gfycat.py

@@ -1,5 +1,3 @@
-import re
-
 from .common import InfoExtractor
 from ..utils import (
     int_or_none,
@@ -11,6 +9,7 @@ from ..utils import (
 
 class GfycatIE(InfoExtractor):
     _VALID_URL = r'https?://(?:(?:www|giant|thumbs)\.)?gfycat\.com/(?i:ru/|ifr/|gifs/detail/)?(?P<id>[^-/?#\."\']+)'
+    _EMBED_REGEX = [rf'<(?:iframe|source)[^>]+\bsrc=["\'](?P<url>{_VALID_URL})']
     _TESTS = [{
         'url': 'http://gfycat.com/DeadlyDecisiveGermanpinscher',
         'info_dict': {
@@ -82,14 +81,6 @@ class GfycatIE(InfoExtractor):
         'only_matching': True
     }]
 
-    @staticmethod
-    def _extract_urls(webpage):
-        return [
-            mobj.group('url')
-            for mobj in re.finditer(
-                r'<(?:iframe|source)[^>]+\bsrc=["\'](?P<url>%s)' % GfycatIE._VALID_URL,
-                webpage)]
-
     def _real_extract(self, url):
         video_id = self._match_id(url)