[DiscoveryPlus] Allow language codes in URL

Closes #1425

yt_dlp/extractor/dplay.py

@@ -325,7 +325,7 @@ class HGTVDeIE(DPlayIE):
 
 
 class DiscoveryPlusIE(DPlayIE):
-    _VALID_URL = r'https?://(?:www\.)?discoveryplus\.com/video' + DPlayIE._PATH_REGEX
+    _VALID_URL = r'https?://(?:www\.)?discoveryplus\.com/(?:\w{2}/)?video' + DPlayIE._PATH_REGEX
     _TESTS = [{
         'url': 'https://www.discoveryplus.com/video/property-brothers-forever-home/food-and-family',
         'info_dict': {
@@ -343,6 +343,9 @@ class DiscoveryPlusIE(DPlayIE):
             'episode_number': 1,
         },
         'skip': 'Available for Premium users',
+    }, {
+        'url': 'https://discoveryplus.com/ca/video/bering-sea-gold-discovery-ca/goldslingers',
+        'only_matching': True,
     }]
 
     _PRODUCT = 'dplus_us'