[FIX] - FIX for MP3 audio out of sync on xbox 360.
i think all xbox 360 user have this issue with plex if your video use MP3 for audio.
so after looking on the forum i finally found the answer. (all credit go to: Darkholme)
HOW TO FIX:
1.Find your plex folder. ex: C:/Program Files (x86)/plex/Plex Media Server/Resources/Profiles
2.Now you should see xbox 360 app, xbox 360 xml files.
3.Download this two xml files Download link.
4.Extract the two xml files overtop of the ones in the folder.
now your MP3 video should be fine, enjoy !