The Default Folders By default all of the image folders are kept in the image folder in the Master Data File. Typically this folder can be found at C:/Synapx/MasterData/Images. Inside this folder you will see several folders that contain images. These folders make up the image subsets in the palette. For example, if the Image folder contains a folder called "Misc" and another folder called "Backgrounds" then the Image tab on the palette will give you access to the "Misc" image set and the "Background" image set. Adding a new folder to the Image folder will add a new image subset to the palette.
The movies are organized the same way as the images. The movie folder is located at C:/Synapx/MasterData/Movies. Any movies you place in a subfolders of this folder will be accessible through the palette.