Burning .iso image to DVD

I am trying to make a copy of a DVD of a recent live performance. When I tried the "Copy CD/DVD" tab using the hard drive method, I got a buffer underrun error and it failed to burn. I decided I might try to make an .iso image and burn that since I've had no trouble burning data DVDs. When I go to open the .iso file, however, the "Make" field automatically resets from "Data DVD" to "Data CD" and gives me an error since I have a DVD loaded and not a CD. This video is a shade over 2GB! How can I get an .iso image file to burn to DVD!?

Thanks for any help on this.

Seth