以下哪一项正则能正确的匹配网址: http://www.bilibili.com/video/av21061574()
/^(https?:\/\/)?([a-zA-Z\d]+).bilibili.com\/?video\/av(\D{1,8})\/?$/
/^(http:\/\/)?(\w+)\.bilibili\.com\/?video\/av(\d{1,8})\/?$/
/^(https?:\/\/)?(\w+)\.bilibili\.com\/?\w*$/
/^(http:\/\/)?([a-zA-Z\d]+).bilibili.com\/?video\/av\w*\/+$/