Rick Drasch the developer behind many great Media Center addins has a new addin called Media Center Search. The application enables you to search for a specific text string in the Media Center TV file metadata (dvr-ms and WTV). You can download the app from his site priced $1.99
Optionally search the Episode Title, Description, Actors and/or Director fields of all the recorded TV files in the Media Center Watched Folder list.
The Actors search also includes secondary credits which are sometimes included in the metadata. Media Center does not display these secondary credits. See the video demo for an example.
The search returns a list from which you can select and Play recordings.