@Nicholas
Trust me, it was hard to find HD productions. Almost no one was shooting in HD in 2003, Lucas and Rodriguez were exceptional and experimental in this regard. Think of the preportion of the amount of theatrically distributed feature films that were shot HD to the amount shot on film from 2003 to 2005. 1:1000 maybe? You can practically count the HD ones on your hands. You have Lucas, Rodriguez, one-offs like Collatoral, and, uh...Lucas? I never even saw an HD camera until 2004, and I never used one until 2006. 2005 is around the time you finally saw them being used here and there, but it was still pretty unusual, the "new" thing. Documentarians began using them first--the Cinealta that Lucas used was not intended for feature filming--because of the long-format tapes, but the cameras were so incredibly expensive that most people just shot on stuff like Digibeta if they wanted to go video. Hell, into 2006 I was still working with Digibeta here and there. And then when the cameras started being adopted for feature use, no one wanted to use them, from the producers standpoint because they were costly and slowed down your post flow, and from the camera crew's standpoint because they were cumbersome, delicate, awkward and difficult to use. I protested the use of HD cameras until 2008 or so when they finally started getting their act together and designing models with feature filming in mind. The older ones that Lucas and Rodriguez were using were simply pieces of junk. It cost the production more money than film, it frustrated the camera crew because they were so bulky and tethered by wires, it frustrated the cinematographer because it restricted his shots and made him compromise his lighting, it frustrated the post people because it was sometimes difficult to work with and was often slower than with a film daily, it frustrated FX people because there was no detail or range to work with so they had to spend more time, and the results looked like shit on the screen at the end of the day. So there was absolutely no point in bothering when film was cheaper, easier, and looked beautiful.
Finally, as Harmy pointed out, DVD extras were usually made like corporate videos and promotional stuff, pretty low budget, small crew, small production, not intended for long-term viewing or high-end viewing. I don't think people started shooting extras in HD until HD formats like Blu Ray came along, and even then most the extras you see even today are not in high def.