ruby-youtube-downloader.rb

#!/usr/bin/env ruby

require 'cgi'

def video_token(video_id)
  token = CGI.parse(%x!curl http://www.youtube.com/get_video_info?video_id=#{video_id}!)['token'][0]
end

def video_id(url)
  CGI.parse(url.split('?')[1])['v']
end

url = ARGV[0]

download = "http://youtube.com/get_video?t=#{video_token(video_id(url))}&video_id=#{video_id(url)}&asv=2"

%x!/usr/bin/env curl -L -C - -o test '#{download}'!