The way file associations are handled by the OS X interface for MediaInfo pollutes the UTI conformance space. By declaring a whole bunch of media file extensions as (only) conforming to 'public.data' other apps may stop working.
For example, with Perian installed QuickTime Player can play MKVs and right-clicking an MKV will normally show QuickTime as an app to open the file with. However, when MediaInfo is installed, QuickTime will no longer show up in the menu and no longer accept MKVs.
The fact that the imported UTIs of MediaInfo break the behavior of other apps is definitely a bug in OS X, but it would be correct to be more careful when setting up your UTIs and declaring the most specific conforming UTI (e.g., public.movie).
I lack of technical skills with Mac OS X :(, but I'll try to find a way to change the behavior.
Do you know about this stuff in Xcode?
I have in plist file:
<key>UTTypeConformsTo</key>
<array>
<string>public.data</string>
</array>
<key>UTTypeIdentifier</key>
<string>net.mediaarea.mediainfo.mediafiles</string>
<key>UTTypeTagSpecification</key>
<dict>
<key>public.filename-extension</key>
<array>
<string>264</string>
(...)
If I change public.data to public.movie, is it enough?
Some file extensions are pure audio, so I think I'll separate in public.movie and public.audio (trusting http://www.escape.gr/manuals/qdrop/UTI.html )