These are the steps that I did:

1 - Install and execute the game for the first time in game mode (it crashed and close) 2 - Change to desktop mode 3 - Install ProtonUp-Qt from the Discover App 4 - In ProtonUp-Qt I installed GE-Proton7-51 5 - Copy from a windows pc (I have a windows 10 pc) these files:

C:\Windows\System32\mfperfhelper.dll
C:\Windows\System32\VIDRESZR.DLL
C:\Windows\SysWOW64\mfperfhelper.dll
C:\Windows\SysWOW64\VIDRESZR.DLL
  

to your steamdeck in these folders:

/home/deck/.local/share/Steam/steamapps/compatdata/1034860/pfx/drive_c/windows/system32
/home/deck/.local/share/Steam/steamapps/compatdata/1034860/pfx/drive_c/windows/syswow64

6 - in both folders rename VIDRESZR.DLL to vidreszr.dll (UPPERCASE to lowercase)

7 - download this https://archive.org/download/mf-install/mf-install.zip and unzip it anywhere as a folder with this structure:

system32/
syswow64/
mf.reg
mf-install.sh
README.md
wmf.reg

8 - copy mfperfhelper.dll and vidreszr.dll (all lowercase) into these folders too [system32 and syswow64]

9 - open mf-install.sh in a text editor and add the next lines (at the end of the file):

override_dll "vidreszr"
wine regsvr32 vidreszr.dll
wine64 regsvr32 vidreszr.dll

10 - right click mf-install.sh go to properties and one of the tabs has a checkbox saying "Is Executable", check that.

11 - open the terminal (in the folder that contains mf-install.sh) and execute the next command:

WINEPREFIX="/home/deck/.local/share/Steam/steamapps/compatdata/1034860/pfx" PROTON="/home/deck/.local/share/Steam/compatibilitytools.d/GE-Proton7-51" ./mf-install.sh -proton

12 - then in game mode go to grandia and in the property window set compatibility to GE-Proton7-51

I did all of this and the FMV is working and the game has not crashed.