It's in the hdd0/VIDEO folder. It stores into separate folders according to name for me, eg:-aa,bb,cc
Inside there are 3 files, acc. to me they are the files for the Icon. Just copy those from another video on your PS3. I would like to know if there are some folders which actually store codecs on the PS3 which I may be able to modify and hopefully enable support for mkv and FLAC.