Resident Evil Revelations use WMP9 to play its Cutscene, and since that is not part of Proton or Wine, you have to install it manually.
First, you need to start the game in proton 5.0. Don't play. Just start it, so it creates the prefix folder in steam.
If you want to know how to install protontricks, you can check it here.
First, open the Terminal.
Then put this command in the terminal and push enter.
PROTON_VERSION="Proton 5.0" protontricks 222480 -q wmp9
I always use winetricks, but sometimes you can't because you don't have permission to do so, and that's where protontricks come in handy.
if you want to use WINEPREFIX, then Open Terminal and then put this command into the terminal.
WINEPREFIX=~/.wine winetricks wmp9
Depending on what you use, you need to edit the WINEPREFIX to the folder that you need to install it to, like RER's prefix folder or Wine folder.
It will download and install WMP9, and when it's done, the game should now show the cutscenes.