I just encountered this exact issue. I’d gladly provide the crash data the game has created, if a private channel to do so is available.
Some facts about my system:
Windows 11
Native res 2560x1440
Game res 1920x1080
CnCNet 9.1.0
Red Alert 2 from Origin
The crash is 100% reproducible by launching the Weathered Alliance mission from the CNCNet launcher. It always crashes at the same playback position in the video.
My guess: The video file/data is somehow damaged.