There is only one file type that uses the .TBN extension:
Kodi Thumbnail Image
Image file used by Kodi, a software media player for Mac, Windows, and Linux; saves a thumbnail image of a video clip, audio clip, or a playlist; used as the preview image when browsing the computer's digital media collection.
TBN files are .JPG files that use the ".tbn" extension. Therefore, you can open them with any standard image viewer or editor.
TBN files use the same filename prefix as the media files they preview. For example, MyVideo.avi would have a thumbnail file named MyVideo.tbn.
NOTE: Kodi was formerly known as XBMC.
Updated: October 7, 2014