I have recently added support for Sony Vegas session files (Veg) to MediaSweeper.
MediaSweeper will show you all the used & unused files for each project and optionally move the unused files to another location for subsequent deletion.
Handy for letting you know ecactly where the media is located for a particular project and if it actually exists for a project.
Also works for multiple projects which share media as well as a heap of user defined file specs.
Donationware of course so if you find it useful then show your support.
MediaSweeper - Adobe Audition® / Reaper File Cleanup Utility