Purchase and download the digital editions of your choice. Click and drag your files from your media library -- be it iTunes or some other provider -- and onto your desktop.
Save the files to your thumb drive. The drive must be inserted into one of your computer's USB ports for it to save correctly. To properly eject the drive after the saving process is complete, simply drag the "USB Drive" icon from your desktop to your trash can (Mac) or recycling bin (PC).
Insert the thumb drive to the second controller port at the front of the PlayStation 3 (PS3) console. The first port is reserved for the controller that will serve as your remote for the duration of your movies.
Select the "Video" icon from the XrossMediaBar (XMB) menu. In the drop-down video menu, select "Device." Another menu will then pop up displaying a list of readable files on your thumb drive. Select the movie of your choice. It will then begin playing.