fix bing videos engine

    dom = html.fromstring(resp.text)

    for result in dom.xpath('//div[@class="dg_u"]'):

        # try to extract the url

        url_container = result.xpath('.//div[@class="sa_wrapper"]/@data-eventpayload')

        if len(url_container) > 0:

            url = loads(url_container[0])['purl']

        else:

            url = result.xpath('./a/@href')[0]

            # discard results that do not return an external url

            # very recent results sometimes don't return the video's url

            if url.startswith('/videos/search?'):

                continue

        title = extract_text(result.xpath('./a//div[@class="tl"]'))

        content = extract_text(result.xpath('.//div[@class="pubInfo"]'))

        thumbnail = result.xpath('.//div[@class="vthumb"]/img/@src')[0]

        url = result.xpath('./div[@class="mc_vtvc"]/a/@href')[0]

        url = 'https://bing.com' + url

        title = extract_text(result.xpath('./div/a/div/div[@class="mc_vtvc_title"]/@title'))

        content = extract_text(result.xpath('./div/a/div/div/div/div/text()'))

        thumbnail = result.xpath('./div/a/div/div/img/@src')[0]

        results.append({'url': url,

                        'title': title,

                        'thumbnail': thumbnail,

                        'template': 'videos.html'})

        # first page ignores requested number of results

        if len(results) >= number_of_results:

            break