利用urllib.request进行爬虫， 下载百度视频页面的所有图片保存到本地(Use urllib.request for crawl. Download all the pictures from Baidu video page to local.)

爬取百度图片，图片质量为medium，可自定义关键词与数量(Download Baidu images with medium quality, and users can customize keywords and number of images to download.)