Why can I get some of my files to play on Plex Media Center and others won't
1. VIDEO_TS, ISO and IMG files are not supported on remote computers.
Streaming of VIDEO_TS, ISO and IMG files when your Plex Media Server and Plex Media Center are on separate computers is not supported. If the Media Server and Media Center are both running on the same computer then you will be able to play these files with mixed results. By mounting the drive where the files are located on your server on the computer running Plex Media Center, you will be able to play the files with mixed results as well.
If you have decided to use Plex long term then we suggest converting those file types to either MKV or MP4 using a free app like MakeMKV or Handbrake. There is no support for these file types in any other Plex Client so if you plan on using one of the Mobile or Connected clients then converting these files is required.
2. The file is not a supported file type in Plex.
Some DVD ripping software, Blu Ray ripping software or PVR software creates proprietary files that only work with there software. Plex will most likely not even recognize these files in the library. The best way to get around to convert the file into something Plex will play with Handbrake.
3. Files with DRM will not play in Plex.
DRM stands for Digital Rights Management. It is included in video files that you purchase online from places like the iTunes and Amazon video stores. Any file with DRM in it will not play in Plex. This includes Ultraviolet digital copies of movies found on Blu Ray discs and offered by places like Walmart that "digitize" your DVDs and Blu Rays.
4. Did the file get deleted or moved?
Check in Plex Media Manager to see if the file is still there or if there is an icon with a yellow exclamation mark on the file. If the file is no longer there or the icon is there, check your drive to see if the file still exists. What does the yellow exclamation icon mean?
5. Check to make sure there isn't a problem with the file by playing it in another media player like VLC.
VLC Uses a similar video engine as Plex. If the file will not play in Plex or VLC then there is a problem with the file. Do not use Quicktime to make this comparison as it uses a different video engine than Plex.