You'll need a USB stick to connect to your PS3. When you're in the Photo menu on GT5, export the image(s) you want to the PS3, then on the PS3 home page, go to photos and then find the ones you want to export to the USB, then copy them onto it by going onto the options menu (press Triangle) and hitting Copy. If you have more than one picture, hitting Copy Multiple up the top speeds things up, and you can also select multiple photos in GT5 and export them to the PS3 all at once.
Again, replays aren't technically speaking videos. They're just game data for recreating a race you saved a replay of. If you need to upload one or something though, you'll find them in the Saved Data Utility of your PS3 and NOT in the Video section.