下载数值分析的视频

download_14_lectures.rb

require 'rest_client'
require 'nokogiri'

HOST = 'http://moocs.nccu.edu.tw'.freeze
html = Nokogiri::HTML(RestClient.get(HOST + '/course/14/section/lecture').body)

html.css('li.lecture>.main>.title>a.link').each do |lecture|
  href = lecture.attr('href')
  title = lecture.css('.value').first.attr('title')
  page = Nokogiri::HTML(RestClient.get(HOST + href).body)
  href = page.css('.srcFrom>a').first.attr('href')
  system 'youtube-dl', '-o', 'title.%(ext)s', href
end