MediaExtractor is the app for you if you need:
In fact, MediaExtractor let you extract all the media files you added to your iWork documents with a simple drag-and-drop.
How does it work? First you have to open the iWork document with MediaExtractor, or drag the iWork document to the MediaExtractor app icon, or open the document using the proper menu within MediaExtractor. Then you can just drag the files you need from the app browser to wherever you want. That's all.