To export a replay data you must have a USB drive. Files are generally 313kb and less when zipped.
Steps:
1. Drive in practice mode finishing at least one lap. Quit the session to return to practice mode menu.
2. Save ghost of fastest lap
3. Exit practice mode and return to the GTLIFE menu. On the set of left icons there is a REPLAY THEATER. Enter the REPLAY THEATER.
4. You will now have access to your saved replay data which include your most recent fast laps and/or races. Select the file you wish to upload.
5. A number of options come up such as play, delete, data logger, and most importantly for this, EXPORT TO SAVED DATA UTILITY. Select EXPORT TO SAVED DATA UTILITY and save the file. A new file will be created on your PS3.
6. Exit Gran Turismo 5 and return to the XMB menu. Under the GAMES category search for SAVED DATA UTILITY(PS3). You will see your GT5 save data which consists of your career and arcade data and a separate file labeled the REPLAY DATA. With your USB Drive inserted in to the PS3 select the replay data and "copy" to the USB drive.
7. Remove your USB drive and go to your computer. Watch some pron.
8. Open the USB drive and there will now be a PS3 folder. Take that folder and use winzip, winrar, or any other compression program and compress it.
9. Upload on to you're post by replying to a thread in "advanced mode" where a manage attachments tab will be located at the bottom of your screen. "Browse" to find your PS3 Zip folder and then click "upload". Let the upload finish and then continue with your thread post.
To view data on your PS3 you essentially do the above steps in reverse order. There will be an IMPORT SAVED DATA in the replay theater. You'll be importing files so that's the button you want to use. The Replay Data will now be available for viewing in your list of saved replay files.