There is no way to do this without some sort of computer. It doesn't have to be a Mac, nor does it have to be your computer.
If the movies are on your camera roll, then if you connect it to any computer it will look like a camera, and you can transfer them using built-in or 3rd party camera software, and use your favorite program (many free ones out there) to write it to DVD. You do *not* have to sync the phone to the computer for this to happen.
You can also save the movies to a stream, click "People", share as a public link, and download the movie to any computer from the web.
There are also adapters that will allow you to watch movies directly from your phone, but of course it's very dangerous not to have a backup.