Thanks Ashdnazg ! Congratulation for modding it ! So it's now definitely established that it is impossible to mod this file to make it fit in RTW, correct ? (Sorry I'm a total newbie in coding... )

So I may have another idea... Do you think it could be possible to "mod" some Shogun files so that nothing appear on the menu screen except that background ?
Example : modding the file that control the "Daimyo selection screen" so that the program won't load the images, icons for selecting a Daimyo, etc... and that we only have a screen with the moving background and nothing on top of it ?

If so, a simple program to film the screen would allow to create a movie of that moving background.

Sorry if this sound stupid for a coder's eyes... I hope it at least make you grin...