I've used this method from my iPhone to my iPad for use with Avid, but should work nonetheless.
1. Plug iPod into pc/Mac and take the file off the same way as photos, ie. navigate to picture/video folder. On a PC (which I use) the dialog pops up when I connect the iPhone to the PC to accesses file folder on the device.
2. Drag said video from the folder to a folder on your PC/Mac specifically for holding these files. I call mine iPad video.
3. Fire up iTunes and plug in the iPad
4. Click on the iPad on the left hand column to bring up the iPad's tabs. go to Photos tab and make sure syncing is enabled. Click to add a folder to share and link to the folder mentioned above.
5. Sync iPad and all photo/ video files in that folder should move across to the iPad. You can check this on the iPad by opening the photo app and you should see a gallery/folder called the same name as the shared folder eg. iPad video
You should be able to access the video files from within iMovie by selecting from camera roll.
Hope this helps!