das.rb

# gem install mechanize
require 'mechanize'

class Download

  def initialize(site, email, pass)
    @options = {site: site, email: email, pass: pass}
  end

  def call
    agent = Mechanize.new
    page = agent.get("#{@options[:site]}/screencasts/users/sign_in")
    form = page.forms.first
    form['user[email]'] = @options[:email]
    form['user[password]'] = @options[:pass]
    form.submit

    agent.page.links[1].click
    arr = agent.page.search('.episode')
    if arr.any?
      puts ".episode attribute found!"
      arr.each_with_index do |l, i|
        agent.get(l.search('a').attribute('href'))
        title = agent.page.title.strip
        agent.get( agent.page.search('script').text.split("\"")[7])
        agent.page.save("#{i} - #{title}.mp4")
        puts "Downloading #{i} - #{title}..."
        title = ""
        2.times { agent.back }
      end
    else
      puts "No .episode attribute found!"
    end
  end

end

Download.new('https://www.destroyallsoftware.com', 'your@email.com', 'yourPass').call