The in game intro can be replaced with another of your choice. First get the video you want to use at 1280x720 or less(I don't know how to get it to accept 1920x1080) get RAD Video Tools and bink it(convert to .bik).
extract movies.pack, rename your .bik video to intro and replace the intro.bik with yours(it didn't work the first time for me so you might have to try it several times with different names) then create a new pack with your video in it. I decided to call it movies3.pack. You should then see your intro video when the game starts. You can also change or remove the subtitle for it by changing it in subtitles.loc, I believe it was in local_en.pack
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I also wanted to figure out how to add a video for the first time you recruit a unit. I modified the The_Sekigahara_Campaign_v0.95_Main_Database.pack, version .95 found here http://www.twcenter.net/forums/forumdisplay.php?f=1841 Tested with murakami in pack 3.
changes/additions
units_tables added unit_ashigaru_naginata_yumi in unit_recruited_movie column
movie_event_strings.loc added a row movie_event_strings_title_unit_ashigaru_naginata_yumijapanese, Yumi-Naginata Ashigaru
added movie_event_strings to seki pack based off of patch24.pack. unit_ashigaru_naginata_yumi, japanese, Training/Land/TRN_YUMNAG.bik, 871
added videos_tables-videos to seki pack based off of patch24.pack. added row Training/Land/TRN_YUMNAG.bik, CAMPAIGN_WIN, 1
Made a pack off of movies.pack which I called movies3.pack. movies3.pack-movies-training-land-trn_yumnag.bik video added(about a 15 second video showing the yumi-naginata ashigaru) The video appears the first time a yumi-naginata ashigaru is recruited.
For recruitment video subtitles. Add a row for your new unit in db--subtitles_tables--subtitles, db--videos_subtitles_junctions_tables--videos_subtitles_junctions and text--db--subtitles.loc I built it off of patch24.pack and local_en.pack using the yari ashigaru line for comparison.There's a problem for additional units http://www.twcenter.net/forums/showthread.php?p=12202459#post12202459