The NX5U is not a tape camera as you already know. The NX5U delivers AVCHD files. The BEST option for you is to purchase either FAST SONY DUO cards or a lesser priced alternative- SDHC CARDS. Make sure your SDHC cards are CLASS 6 and above. Purchase a fast USB card reader. Place the USB cable into your unit from the CARD READER and OPEN up a PROJECT designated as HD. Use a card reader instead of the camera’s USB jack. Reported sporadic incompatability with other systems when using the USB jack directly from the camera.
The NX cameras are having a problem, it is called a BUFFER-OVERFLOW when using BOTH internal and external drives in tandem. SONY are working on a firmware update. However, be careful not to blame your unit if you have a problem with the card. There are reports of individuals losing their work due to the BUFFER problem.