One minor nitpick, these tags are not EXIF tags, they are Quicktime tags (all EXIF is Metadata, but not all Metadata is EXIF). You can add
-G1 to your command to see the group they belong too. Additionally, if you add
-a to your command, you will probably see that
MediaCreateDate are duplicated, one for each track in the file (video, audio, etc).
CreateDate is probably the most accurate, but if the video is coming directly from a digital camera of some sort, it is probably the same value as
Video metadata isn't my expertise, but I would guess that
Track/MediaCreateDate leaves open the possibility of keeping track of an earlier created video/sound track and muxing them together for a final product. Something that might pop up if your editing various video clips together.
One thing to take note of is that these three tags are supposed to be recorded in UTC time. See fourth paragraph on the Exiftool Quicktime tag page. The trouble is that some cameras do not adhere to the specs, so the time that appears in the above tags may not at first seem to be the correct time.
CreationDate is obviously different. It includes a timezone and is part of the QuickTime Keys Tags
and isn't editable by exiftool (now editable with exiftool ver 11.39 or greater). I otherwise can't really comment on it as none of the few test vids I have use that tag.