CommentStreams:E5d47020791a2de7c9b020b2c0e0299f

The "Complete Set" box has a listed runtime of 205 minutes. As you mentioned, each individual commercial DVD volume has a listed runtime of 60 minutes, making them a total of 180 minutes. Therefore, the fourth disc exclusive to the box is included in the total 205 minute runtime, and must be about 25 minutes.

The total runtime of all the monthly DVD-R releases, on the other hand, seems to add up to exactly 400 minutes. So, even if the physical releases consist entirely of footage recycled from the monthly burned discs, that leaves 195 minutes unaccounted for, and therefore lost as far as we know.

And I'm sure you're right about the romaji. The "tsuki gou" was taken entirely from Google Translate, which is far from the best way to romanize any language.