Where are my iPod videos after I sync to iTunes?
iTunes doesn't sync videos/photos back from your device. The Photos tab in iTunes for the device is only for syncing photos/videos from an iPhoto/Aperture library or folder to your device. It doesn't sync the other way — from your device to the library/folder.
You need to use something like iPhoto/Aperture or Image Capture.

 Transfer images and other items from your device
Transfer images, video clips, and MP3 sounds to your computer from many cameras and devices that contain a camera, such as your iPhone. Once you transfer the items, you can delete them from the device.


Connect your device to your computer, then turn the device on.
If the device is locked with a passcode, enter it.

In Image Capture, select the device in the Devices list.

Use the buttons at the bottom of the Image Capture window to view the thumbnails as a list or as icons to change the size of the thumbnails, or to rotate or delete images.

From the Import To pop-up menu, choose where to save the images or which app to use to open the image.

To import only some of the photos, select those photos, then click Import. To import all the photos, click Import All.
Choose AutoImporter from the “Connecting this [device] opens” pop-up menu to transfer images from a device to your computer whenever you connect it to your computer.

Select “Delete after Import” to remove the items from the device after transferring them to your computer. You can also select individual items on your device, then press the Delete key on your keyboard.



Source: OS X Image Capture Help