- 1). Hook up your iPod Nano to your computer using the USB link cable. Open iTunes.
- 2). Open your device settings pane by clicking on your Nano's name in the "Devices" area on the left.
- 3). Enable manual sync by clicking "Manually manage music and videos."
- 4). Click "Movies" in the "Library" section on the left. This is different from clicking the "Movies" tab in the main panel. After clicking this, your movie library appears in the main panel.
- 5). Click and drop movies from the main panel onto your iPod Nano's icon in the left panel. The movies sync without erasing any content once it is dropped onto the icon.
Source...