这里主要是主要非贪婪量词的用法， .+?"的意思是匹配任意字符，直到遇到第一个"
另外是找到匹配的组，如下x[0]
require 'open-uri'
open('http://railslab.newrelic.com/category/masters-interviews') do |f|
s=""
f.each { |line| s<<line}
urls= s.scan(/"(http:\/\/content.newrelic.com\/railslab\/videos\/.+?)"/)
urls.each { |x| puts x[0].to_s }
end
结果是取得了所有rialslab里masters-interviews系列。
http://content.newrelic.com/railslab/videos/railslab-rightscale-cloud-considerations-070109.mov
http://content.newrelic.com/railslab/videos/railslab-rightscale-cloud-considerations.m4v
http://content.newrelic.com/railslab/videos/railslab-heroku-tools-collaboration.mov
http://content.newrelic.com/railslab/videos/railslab-heroku-tools-collaboration.m4v
http://content.newrelic.com/railslab/videos/railslab-heroku-performance-bp.mov
http://content.newrelic.com/railslab/videos/railslab-heroku-performance-bp.m4v
http://content.newrelic.com/railslab/videos/railslab-heroku-intro-vision.mov
http://content.newrelic.com/railslab/videos/railslab-heroku-intro-vision.m4v
http://content.newrelic.com/railslab/videos/railslab-bbg-jproudman-pt2.mov
http://content.newrelic.com/railslab/videos/railslab-bbg-jproudman-pt2.m4v
http://content.newrelic.com/railslab/videos/railslab-bbg-jproudman-pt1.mov
http://content.newrelic.com/railslab/videos/railslab-bbg-jproudman-pt1.m4v
http://content.newrelic.com/railslab/videos/railslab-productmadness-1.mp3
http://content.newrelic.com/railslab/videos/railslab-productmadness-2.mp3
http://content.newrelic.com/railslab/videos/railslab-cunningham-mastery.m4v
http://content.newrelic.com/railslab/videos/railslab-37signals-imbriaco2.m4v