http://www.cisco.com/en/US/docs/ios-xml/ios/media_monitoring/configuration/15-2mt/mm-pasv-mon.html
There are a ton of new features in the 15.2 train. This is another one I’d like to look into further if I can find the time. Though I do have to say, I’d rather Cisco focus on fixing some bugs for a while over more “neat to have” features, so I can quit spending time on workarounds and have some free time to work on “neat” stuff.