There are 2 primary reasons why files will not show up in a shared folder when you have the stick plugged into your media player -
1. The total size of the cumulative files is over 1 tb or over ~20,000 files. The stick has a hard coded upper limit on the amount of data it can 'see'. You can only have 1 TB or around 20,000 files of data or less mounted at any given time. If you have more than that, you will notice that some files and directories are missing. Managing this could be quite easy as you could setup separate folders and share them individually (such as music, videos, pictures, etc) and sort them by size. Also, any file over 4 GB will not show up on the stick as our software emulates the FAT32 protocol, which has that limit.
2. The media player that you are working with does not support the file type you are trying to use. Most media players with a USB port support MP3 and Divx but others (such as the WDTV and Samsung tv/bluray players) support many more format types (such as mp4 and mkv). If your player does not support your file type, then you can need to use software to convert your files to the proper type. One such program is xvid4psp. http://xvid4psp.en.softonic.com/