如何使用特定的ruby代码获取youtube视频ID？

Question

是否有人有必要更正以下程序，以便从html结果中获取YouTube视频ID。

这是我在Playing youtube music from the command line创建的ruby代码。我正试着让它在我的电脑上运行：

require 'hpricot'  
require 'open-uri'  

playlist=Array.new

 #This thread actually plays the tracks in the playlist then removes them.  
player=Thread.new {  
  while true  
    #If the playlist is empty, play random mp3s until someone adds something  
    if playlist.length==0 then  
      system('./random_music.sh')  
    else  
      system('mpg321 -q '+playlist.shift)  
    end  
  end  
}  

 #While the main thread handles the user interface:  
while true  
  puts "What would you like to listen to?"  
  search_string= gets.chomp  
  puts"Searching for #{search_string}..."  

  #Use Hpricot to load the youtube search page and scrape the titles and ids of the top 5 results  

  doc = Hpricot(open("https://www.youtube.com/results?search_type=search_videos&search_query="+search_string.gsub(' ','+')))
  result_divs=doc.search("div[@id=search-results]/div")  
  results=Array.new

  #Ask the user which one they want  
  for i in 0..4 do  
    #keep the a object as it has both bits of data  
    results[i]=result_divs[i].search("div.result-item-main-content/h3/a")  
    puts (i+1).to_s + ') ' + results[i].inner_html  
  end  
    choice=gets.chomp.to_i    
  if (1..5).include?(choice) then  
    choice-=1  
    youtube_id = results[choice].attr('href').split('&')[0].split('=')[1]  

    #Download/extract the audio in parallel so that more tracks can be added in the meantime  
    Thread.new(youtube_id,results[choice].inner_html) { |id,title|  
      if ! File.exist?(id+'.mp3')  
        puts 'Downloading ' + title  
        system('youtube-dl --extract-audio -w -q -f 5 --no-part '+id)  
      end  
      playlist<<id +'.mp3'  
      puts title+' added to playlist'
    }  
  end  
end