Use K3b to burn the DVD. Select File->NewProject->NewVideoDVDProject. First, double click on the DVD writer. If you have a blank DVD in the drive, it should say that and give you specs on the blank DVD. Look at the sample in Fig 14 to see the description that appears when a blank DVD is in the drive.

Navigate the file system tree (left pane) to the directory that holds the DVD file structure created by QDVDAuthor. Drag the VIDEO_TS directory from the top right pane to the "K3b data project" tree on the bottom pane. You can drag the AUDIO_TS directory if you like, but it's empty and does nothing for you. You should see a bar at the bottom of the window that shows how much of the available space (4.4 GB) will be used. Save the config file in a location of your choosing, I put it in the same directory as the AUDIO_TS and VIDEO_TS directories. When you're ready to burn, click the "Burn" icon and a dialog will pop up. Just make sure the "Simulate" checkbox is not checked. Click this dialog's Burn button and wait for it to finish. Look at the sample in Fig 15 and Fig 16 to see what K3b tells you while it's burning.

Approximate time: 14 minutes on my 4X DVD-RW burner, with Generic DVD-R media.