I use Directory Opus too and I created file type groups and assigned them different colors.
That's what I've done, but just assigning one colour to a media type. It's nice to be able to look at a video folder that contains the associated sidecar and image files and have the actual media files stand out.
On reading glynor's comment, I decided to see what would happen if I turned-off file association for all file types in MC. It had the immediate effect of returning all the icons for those file types to what they were before they were assigned the common MC icon. The actual association, however, remains. So there doesn't seem to be anything lost in doing that. I suppose what might happen is if I open any of those files in another application which is inclined to take the file association, it may do so.
The annoying thing that remains is that all of those file types are still called "Media Center files." In most cases, I can still see what they are from their icon and/or file extension, but I do appreciate having a more descriptive
Type. Maybe it's a Windows issue. It doesn't seem uncommon for File
Types to be named according to the application associated with them, and the same application may be associated with a number of different (I don't even know how to say it...) "extension-types." I've tried and failed to find solutions to the issue using DOpus and other file association utilities, but none offer a way around this.
On the other hand, I've got lots of
Types that remain based on a single file "extension-type," although the application is associated with a number of different types. Microsoft
Types, for example, are of the (annoyingly wordy) form "Microsoft [Application Name] [extension-type];" others use "[Application Name] ([.EXT])." So that would suggest it is under the control of the application taking the association to make one
Type for all it's associations, or to maintain them separately. It seems to me is the keeping them separate that's critical. Even if it uses the same icon for all of them, users would still have the ability to change the icons to something else (and many icon collections, BTW, have nice icons for specific media file types). This can't be done if all the file extension-types have been defined as one
Type.