Sounds to me like you haven't restored an image backup to the new box or it would be an exact mirror image of the original box.
Can you explain how you did the backup and restore process?
When you pressed the green button for the first time to go to plugin browser did you get a message pop up about the Movie Organisor plugin? if so just try restarting gui, hold down power button until menu appears and then select 'restart gui'.
If that doesn't help, on wooshbuild 5.3 you should be able to install the Movie Organisor plugin by pressing the green button twice, and then looking in the Extensions group.
Rebbot the box and it should appear
I've don't do image backups to usb because it takes ages.
Do an image backup to HDD and there should be a zgemma folder in the root of the HDD. (Menu > Setup > System > Software Management > Complete Image Backup (something like that)).
Just copy this to a USB stick and flash with that. (You will need to press the front power button when USB appears on the display).
It should then flash an exact copy of your box.
Are you sure there wasn't a previous flash image on the usb stick? If you've done it correctly you would have an exact mirror image of your box.