Video files organizer for mac
Forgive me if I've missed something, but iTunes organizes video files and meets all of your stated requirements as of the time of this posting.

You can add images to the file's metadata, set the season, and set the episode by right-clicking on the file, selecting 'get info', and entering the data in the appropriate spaces.

iTunes will display files' artwork and split seasons.  It even has different views available in a menu in the upper-right corner of the window.