def get_offer_video_link(html_parser):
    """
    This method returns a link to a video of the apartment.

    :param html_parser: a BeautifulSoup object
    :rtype: string
    :return: A link to a video of the apartment
    """
    video_raw_data = html_parser.find(class_='section-offer-video')
    video = ''
    if hasattr(video_raw_data, 'iframe'):
        video = html_parser.find(class_='section-offer-video').iframe.attrs[
            'src']
    return video
