Hi,
Unfortunately just placing new items in the FTM media folder does not automatically make them appear in the media collection shown in the FTM Media workspace.
In order to make new items appear in the collection you have to use the "Add / Add New Media" option found at the top right of the Media workspace. Once the items have been added to the collection you can then link them to individuals/facts.
It's also possible to add media items from a couple of places on the person workspace. For info, there's a useful video tutorial on using Media that can be found under the "Help / Training Tutorials" menu bar.
Note, you can use the above options to add media items located anywhere on your hard disk, they don't have to be located within the default FTM Media folder. (It just makes a backup easier if they're all in one folder)
Ian.