Ok here goes.
Hope this works for you,
the video you have in Quicktime, as long as its supported by the App itself and not a plugin, will open in iMovie as well.
Open iMovie and create a new project and drag your clip right on in there, it should go in and appear on a timeline at the bottom. Now that its there, check you can hear the sound by playing it back.
Now you're in iMovie you can go to the share button along the top bar and select iMovie, this is iMovie 6 btw, it is different for earlier versions, not that different though.
When you've used the share option it should open iDVD and you just have to choose how you want the menus to appear on your TV and stuff, or if you're not bothered about that, just hit burn disc with a compatible blank DVD in.
Leave to whirr for however long is necessary. When complete extract DVD and fire into your nearest player, enjoy!
If you have any trouble just ask.