I haven't given up on this question yet
I called Mitsubishi and their tech support didn't know either although they gave a possible clue by stating that the A/V Disc had to be HAVi compliant. Further searches on HAVi and perusing the HAVi.org site show that around 2001ish a lot of hard drive manufacturers made a big deal about HAVi in press releases, and then never mentioned it ever again. I called LaCie and asked them, since all of my firewire HDs are made by them, and they had no idea either, but pointed out that I should try contacting the firewire chipset manufacturers to see if it is built into their chipsets. So I sent off emails to the two that I know of OxfordSemi being the one who makes the LaCie chipsets and am hoping to hear back from them soon. I also sent emails to Maxtor and Western Digital as well just to see if they knew something no one else does
So the quest continues, if I find out hard answers on this I will let you know. Think of how cheap it becomes to upgrade your High Definition PVR in the Mitsubishi sets if all you have to do is plug in a IEEE-1394 hard drive
