What file types (or perhaps extensions) classifies as what in the spotlight index?

Dear community!

I'm a fresh OSX user but have extensive knowledge in the world of Windows operating systems as well as various Linux/Unix flavours.

I've come to like OSx a lot as a kind of hybrid of the two and use it on my personal (not for work) notebook at home (MBP15").

I've gotten the hang of most of what is important to me but I' curious to one (or a few) things still. Hoping to sort one of them out with this post

When I click the "About this Mac" in the Apple drop down menu I can get a quick overview of OS, display, disks and memory. On the disks tab I get a breakdown of the disk(s) and thier current content (in terms of content types). On my particular computer I'm told that I have (about) 6Gb music, 3Gb photos, 5Gb apps, 0,5Gb Video, 1Gb backups and 98Gb other. That is nice.. But it's not correct (by any means).

Q: What UTIs are part of each "category" here and more importantly.. How do I change this (so it makes any sense at all)? Ie. if I drop a folder contaning 10Gb of .mkv video files on the desktop, those are considered "Other" (once the spotlight index has refreshed, which sometimes take quite a while). Is there an easy way to "classify" content so they end up in one of the preconfigured categories? (.mkv files shold get recognized as video for example)?

If I do a mdls on one of those files it seems to be "correctly" tagged, already:

mdls House.of.Cards.S01E06.720p.mkv

kMDItemContentCreationDate = 2013-03-22 21:13:22 +0000

kMDItemContentModificationDate = 2013-03-22 23:03:09 +0000

kMDItemContentType = "dyn.ah62d4rv4ge804450"

kMDItemContentTypeTree = (

"public.data",

"public.item"

)

kMDItemDateAdded = 2013-03-23 07:58:28 +0000

kMDItemDisplayName = "House.of.Cards.S01E06.720p.mkv"

kMDItemFSContentChangeDate = 2013-03-22 23:03:09 +0000

kMDItemFSCreationDate = 2013-03-22 21:13:22 +0000

kMDItemFSCreatorCode = ""

kMDItemFSFinderFlags = 0

kMDItemFSHasCustomIcon = 0

kMDItemFSInvisible = 0

kMDItemFSIsExtensionHidden = 0

kMDItemFSIsStationery = 0

kMDItemFSLabel = 0

kMDItemFSName = "House.of.Cards.S01E06.720p.mkv"

kMDItemFSNodeCount = 773681947

kMDItemFSOwnerGroupID = 20

kMDItemFSOwnerUserID = 502

kMDItemFSSize = 773681947

kMDItemFSTypeCode = ""

kMDItemKind = "Matroska Video File"

kMDItemLastUsedDate = 2013-03-28 22:23:25 +0000

kMDItemLogicalSize = 773681947

kMDItemPhysicalSize = 773685248

kMDItemUseCount = 2

kMDItemUsedDates = (

"2013-03-27 23:00:00 +0000"

..or is it in the wrong content type tree? I know there is a "public.video". Perhaps that is the answer!? But how do I change this (in a GUI-kind-of-way, since I will have to do those changes for many file types, from day to day, as new file types gets introduced).

A categorized breakdown of your storage usage is only so useful if it does not reflect the actual content bulk.

Any hints appreciated!