'Parses a string of Youtube IDs such as "1.0:AXdE34_U,1.5:VO3SxfeD"
into a dictionary. Necessary for backwards compatibility with
XML-based courses.'

@classmethod
def _parse_youtube(cls, data):

    ret = {'0.75': '', '1.00': '', '1.25': '', '1.50': ''}
    videos = data.split(',')
    for video in videos:
        pieces = video.split(':')
        try:
            speed = ('%.2f' % float(pieces[0]))
            youtube_id = deserialize_field(cls.youtube_id_1_0, pieces[1])
            ret[speed] = youtube_id
        except (ValueError, IndexError):
            log.warning('Invalid    YouTube    ID:    %s', video)
    return ret
