If you want to write a big (> 4 GB) file to DVD, you must use a burning program that allows you to choose UDF as the format... Otherwise, the burn process will fail, and you will end up with a useless coaster!
Airport Utility v6.0 looks very shiny, but has lost lots of features since the old version. It no longer supports IPV6, syslog, connection monitoring graphs, or WDS (extending a network wirelessly). Happily there is an easy fix...