Overall the best is to use xtool zlib+srep+lolz on almost all files. Audio files seems to be ogg (at least the game has a .dll for ogg) but i tried to use oggre on the .wem files without luck so i leaved it with srep+lolz. For the mp4 files they can be stored for faster compression times or just leave it and use the whole game with zlib+srep+lolz (something like 30 minutes more on compression). Dicctionary size does a good work on this game, with lolz d128 game size is about 8.51 and with d256 size is about 8.42 (but takes 1 hour more, installation time is almost the same). Didnt tried with higher settings. Maybe someone knows a way to compress those .wem files better (lossless) to get it lower.
Nice job, i like your conversion !!!