16 of the 17 pages with an empty slot 4 belong to MSG_DEMO_600..604, whose
caption text matches, word for word, the five resupply lines documented from the
movie side as VOICE_D_450..454. Slot 4 is empty on purpose: that audio binds
through the movie path, not through a DEMO_nnn cue.
That also disposes of the '5 ids with more than one record' item -- each appears
once per stage that uses it, and the repeat counts equal the movie-slot counts
recorded independently for the matching banks: 3/3/4/4/2 both ways, 5 of 5. The
11 extra records over 138 ids are these repeats.
Worth more than closing two items: the cutscene message table and the movie
subtitle chain were decoded from different containers by different routes and
agree on the same five lines with the same multiplicities.
MSG_DEMO_500 remains: one page, KATANA, 2s, no text and no cue.
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