'Creates a cohorted video block, giving access to only the given group_id.'

def _create_cohorted_video(self, group_id):

    video_block = ItemFactory.create(parent=self.unit, category='video', display_name=(u'video    for    group    ' + unicode(group_id)))
    self._setup_group_access(video_block, self.partition_id, [group_id])
