Unfortunately, the file has to be an actual video, or the game crashes.
Install:
- Unzip somewhere.
- Copy the Data folder to your Divinity: Original Sin 2 installation folder (i.e. "Steam\steamapps\common\Divinity Original Sin 2\").
- When asked to confirm replace, replace all.
- What you specifically copied in was: "Data\Localization\English\Video\Splash_Logo_Larian.bk2".
- Success!
Uninstall:
- Delete Splash_Logo_Larian.bk2 within the "Divinity Original Sin 2\Data\Localization\English\Video\" folder.
- Sadness...
Notes:
- Non-editor mods for Divinity: Original Sin 1 & 2 work by overriding existing files, usually packed inside .pak files. Splash_Logo_Larian.bk2 was found in "Divinity Original Sin 2\Data\Localization\Video.pak"
- You can extract DOS2's pak files with Norbyte's Export Tool (forum thread here: http://larian.com/forums/ubbthreads.php?ubb=showflat&Number=572568&page=1). Check the later pages for DOS2 support.