If you use something even as simple as Nero Vision, you can get a fair DVD from an AVI. If you are only bothered about watching the film, in stereo, and in as good quality as off-air (i.e literally just "to see it") then this is an easy a quick(ish) way of doing it. I do it frequently for kids films (well-known CG-animations and fairy tales) and it works fine, (and has the added bonus of I dont really care if the disc gets scratched by over-zealous 4-year-old hands!), you might get the ocassional judder, but you can get away with it.

But absolutely, download the ISO of the DVD-9 anyway and then use DVD shrink to fit it to a DVD-5 if needed. It's definitely the definitive version.