Please note, that if you want to modify file’s EXIF dates via ExifTool, for mov/mp4 files you have to set the setting -api QuickTimeUTC=1 otherwise it will process timezones incorrectly QuickTimeUTC. For other files such setting has no effect, so it’s harmless to use it all the time.
BTW, it’s not datetime related but I remembered also for video files it makes sense to set another ExifTool setting -api LargeFileSupport=1. Otherwise you won’t be able to set EXIF tags for files over 2gb (or maybe 4gb, I didn’t check exactly) LargeFileSupport