Compressor is an app that is usually thought of as an add-on to Final Cut Pro. But it can be purchased by itself in the Mac App Store and used to compress video and burn DVDs. You can take a single video and set some options, such as menu and title screen backgrounds, chapter names and start times and disc name.
Many people often wonder what export settings to use in iMovie in order to create the best DVDs. But DVDs are standard definition, and any video you export from iMovie will be re-encoded into a special DVD format. So it is merely a matter of exporting at the best settings available and then letting your DVD software use the best version of the video possible to create the DVD.