EDIT: I've got my answer; see the next post for links to the videos, and thanks to all who replied!
The Japan Broadcasting Corporation (NHK) has just created in English a website they've had in Japanese for a month or so, streaming some higher-resolution versions of the full Earthrise and Earthset video from Kaguya. They are closer to high-definition resolution than any previous release, but still not there yet. Unfortunately, they don't provide the videos in a downloadable format, only in a streamed format, which is too bad because the stream is really poor quality, showing me just a few frustrating frames of the video. My thanks would go to anyone who can figure out how to convert this to some format that could actually be mirrored elsewhere!