class TeachingChannelIE(InfoExtractor):
- _VALID_URL = r'https?://www\.teachingchannel\.org/videos/(?P<title>.+)'
+ _VALID_URL = r'https?://(?:www\.)?teachingchannel\.org/videos/(?P<title>.+)'
_TEST = {
'url': 'https://www.teachingchannel.org/videos/teacher-teaming-evolution',