Instructions
Make sure your external hard drive is formatted at FAT32. Your PlayStation 3 console will not recognize hard drives formatted as NTFS.
Plug your external hard drive into a USB port on the front of your PS3 console. Plug your hard drive into the main power supply if you can, to avoid the risk of it turning off in the middle of the file transfer.
Turn on your PS3 console and scroll across to "Video" in the main home screen menu. Press the "X" button to access this menu.
Scroll down to the video that you want to transfer, and press the triangle button. Select "Copy" from the menu that appears on the right of your TV screen to transfer the video to your external hard drive, while leaving it on the PS3. Select "Move" to transfer the video to your hard drive and remove it from your PS3.
Choose the external hard drive as your destination device, and press "X" again. The file transfer will begin. Repeat this process for each individual video that you want to transfer.
Unplug your external hard drive from PS3, and plug it into your PC to check that the videos have transferred properly. Open your hard drive, then open the folder called "Video." Your video files should be in this folder.