[youtube:truncated_url] Add hl= forms (#4799)

youtube_dl/extractor/youtube.py

@@ -1688,6 +1688,7 @@ class YoutubeTruncatedURLIE(InfoExtractor):
             feature=[a-z_]+|
             annotation_id=annotation_[^&]+|
             x-yt-cl=[0-9]+|
+            hl=[^&]*|
         )?
         |
             attribution_link\?a=[^&]+
@@ -1707,6 +1708,9 @@ class YoutubeTruncatedURLIE(InfoExtractor):
     }, {
         'url': 'https://www.youtube.com/watch?feature=foo',
         'only_matching': True,
+    }, {
+        'url': 'https://www.youtube.com/watch?hl=en-GB',
+        'only_matching': True,
     }]
 
     def _real_extract(self, url):