Flipped all video files upside-down

Videos can be fixed by flipping them upside-down manually (using ffmpeg), then they will appear correctly in-game; to do so:

• in a terminal, from your Steam library (usually ~/.steam/steam/ or something similar), go to the game assets folder:

cd "<steamLibrary>/steamapps/common/Endless Space 2/EndlessSpace2_Data/StreamingAssets"

• duplicate the "Movies" folder (this will take ~4.2GB extra; this is necessary because ffmpeg cannot convert files in-place):

cp -r Movies Movies.bak

• move into the newly created folder:

cd Movies.bak

• from there, use ffmpeg to v-flip all video files, into the original folder (overwriting original files):

find . -name \*.mp4|xargs -I '{}' ffmpeg -i '{}' -vf vflip '../Movies/{}' -y

• the "Movies.bak" folder may now be deleted, but try running the game first, to make sure all is fine; if needed, Steam can restore the original "Movies" contents using Verify integrity of game files or reinstalling the game.

You may notice the new video files are much smaller than the original ones; you may tinker with ffmpeg encoding/codec options to alter the results, but I found the smaller files to be perfectly fine as well, no noticeable artifacts.