The end result is what is called an "AVCHD disc". The disc itself is your average blank DVD media. The difference is how the HD video is encoded and burnt onto the disc, using the AVCHD codec which is a popular recording format found on many low-to-mid-range camcorders. The disc is not a Blu-ray disc, and the video isn't a Blu-ray video, but it is compatible with many Blu-ray players. A regular DVD player will not play the disc, since the disc doesn't contain any DVD-video files.
(Some versions of DVD Studio Pro allow you to burn a "HD-DVD" which is neither a DVD or a Blu-ray disc. It was a competitor format to Blu-ray in the race to become the most-adopted high-definition disc format, but is now mostly forgotten. This method of burning an AVCHD disc is not related to HD-DVDs.)This, then, is simply a way of getting your HD video out of your computer and into your Blu-ray player without the need for a pricey Blu-ray burner or blank discs. There are of course some caveats. Ken Stone says the length of the video is limited to about 20 minutes due to the smaller capacity of the DVD disc. This method requires Final Cut Pro 7 and a suitable Mac to run the software. Luckily, my work provides me with both of these and I gave it a go.
Unusually for FCP, the process of burning the AVCHD disc appeared to be a little unstable. It took me a few attempts before I had a usable disc; the encoding took hours during which there weren't any prompts to insert or remove a disc. On my last attempt I impatiently ejected the disc after a good long while, thinking that it had had plenty of time to burn correctly, and to my surprise it worked. I'd prefer a bit more confidence in the burning process though, but it looks like my case was an exception.
The AVCHD disc worked perfectly with our film club's Panasonic Blu-ray player, and also my Philips BDP-5200 at home, operating just as a conventional Blu-ray disc would. However I'm not sure I'll be burning AVCHD discs in the future, as I've been testing MKV files on a USB thumb drive and they work well on my Philips player which has a USB socket. For me, this AVCHD disc burning feature in FCP 7 will remain something of a curiosity, and I wonder how much it is used by other FCP editors.