Sitecore RadEditor and Multisite Media Library

Currently working through an upgrade from 6.0.1 to 6.4.1 yea we are a little behind but we need to catch up and start using some of the features. We have 18 sites in a single Sitecore instance. And about 250,000 items in that tree. During the upgrade process our problem and so far only one we have run into is our custom Media Library. Each site has its own Media folder with a separate Images, Videos, and Audio folders. This makes ownership and maintenance a little easier. How did we do this? There is an override of the InsertImageForm (picture coming soon) that calls a sitecore query: similar to this.

targetPath = "query:ancestor::*[@@templateId='{18F42371-1B85-4EE1-AF6B-20F5AF81BD5D}']/Media";

This uses a technique very simliar to Alex Shyba's example on how to remember the last section when working with Media. Once we deployed 6.3 we ran into an issue where this no longer works. The query appears to be failing and we end up with the default Media Library being displayed. This means that all of our sites no longer have access to their unique media content. My mission this week is to use .NET Reflector and see what's changed in the Sitecore.Kernel.dll and how this override of InsertImageForm needs to be altered. Any suggestions?