I dont' want to sound too dismissive, but considering the platform (number of 3rd party apps) and common use-cases (how many applications have user-exposable media ?), this is the wrong solution. I'm certain applications should opt-in media files and not opt-out, especially if you operate on SD level. This is why fremantle / trackerd integration CAN be smart, files belonging to debs could and should automatically be ignored f.e. by the application installer (either directly or through MAFW if possible). Otherwise, chances are almost all of 'extras' will do it wrong at first, have a bug filed, have it corrected by the author or the community, make a patch, distribute it, make wikis about it, make sticky posts with giant letters addressing developers, maybe even making a patch to the garage autobuilder to this automatically because all of the above failed, etc. This could all be avoided with a proper approach in the beginning and it's not that hard to do.