Also running it again with the latest static build of ffmpeg and get this on beginning export:
objc: Class FIFinderSyncExtensionHost is implemented in both /System/Library/PrivateFrameworks/FinderKit.framework/Versions/A/FinderKit (0x7fffa6939210) and /System/Library/PrivateFrameworks/FileProvider.framework/OverrideBundles/FinderSyncCollaborationFileProviderOverride.bundle/Contents/MacOS/FinderSyncCollaborationFileProviderOverride (0x12f160dc8). One of the two will be used. Which one is undefined.
Not complete yet, but I will let you know if that causes an issue