NokoGiri selectors vs Ruby loops

noko_v_ruby.rb

require 'benchmark'
require 'nokogiri'
require 'open-uri'

class PageScraper
  
  def self.get_youtube_urls(url)
    self.new(url).get_youtube_urls
  end
  
  def initialize(url)
    @doc = Nokogiri::HTML(open(url))
  end
  
  def get_youtube_urls
    youtube_page_links.map{|link| link.attribute('href').to_s}
  end
  
  def find_css_elements(selector = 'a')
    @doc.css(selector)
  end
end


class PageScraperNoko < PageScraper
  def youtube_page_links
    find_css_elements('a[href*="youtu"]')
  end
end

class PageScraperRuby < PageScraper
    
  def get_youtube_urls
    youtube_page_links.map{|link| link.attribute('href').to_s}.
               delete_if {|href| !(/youtu/.match(href)) }
  end
  
  def youtube_page_links
    find_css_elements('a')
  end
end

URL = "http://ask.metafilter.com/252306/Looking-For-Songs-That-Have-A-Dark-Driving-Beat"

iterations = 100

Benchmark.bm do |bm|
  bm.report do
    iterations.times do
      PageScraperNoko.get_youtube_urls(URL)
    end
  end

  bm.report do
    iterations.times do
      PageScraperRuby.get_youtube_urls(URL)
    end
  end
end


# results
#     user     system      total        real
# 1.060000   0.120000   1.180000 ( 21.660606)
# 1.000000   0.110000   1.110000 ( 19.030504)