The PureMVC Framework Code at the Speed of Thought

Hi, I am new to PureMVC and MVC in general and I need help architecting my first PureMVC application.
Basically, my application loads a playlist from an external xml and populates a tilelist with thumbnails of the videos. When you click on a thumbnail it will load the video in the video player and plays it. The urls of thumbnails/flvs are blowfish encrypted in the xml therefore the proxy needs to decryptthem once the xml is loaded. On a side note, is there any point in using blowfish in flex when swf files when can easily decompiled to expose the key?

Should I create:
- a PlaylistProxy which will load the xml using a PlaylistDeligate, create VideoVOs containing the decrypted thumbnail jpg url and flv url, pass it in the notification and let the component load the thumbnail and flv using the urls?
- a PlaylistProxy which will load the xml using a PlaylistDeligate, create VideoVOs which contains the loader for thumbnail and netstream,netconnection for flv file ready for the component/mediator to use?
- a PlaylistProxy which will load the xml using a PlaylistDeligate and load the thumbnail and video data separately using VideoProxy+VideoDeligate and ThumbnailProxy+ThumbnailDeligate?

or is there a better way to do this? I am confused about the extent I should go with MVC. Should deligates only be used for serverside script access? or for any file that is loaded externally?