if m_urls is None or len(m_urls) == 0:
raise ExtractorError(u'Unable to extract video url')
# They are sorted from worst to best quality
m_url = m_urls[-1]
if m_urls is None or len(m_urls) == 0:
raise ExtractorError(u'Unable to extract video url')
# They are sorted from worst to best quality
m_url = m_urls[-1]