Also look at the /etc/bash_completion file for media filetype that aren't expanded by tab completion after entering the player name in the terminal.
There should be a line where media filetypes are defined and inserting the filetype (e.g. flv|FLV) into the list will enable that file extension for tab completion of arguments.
So one may easily add a filetype without having to fully understand the tab completion file which can get pretty hairy. Grep for your application, another media player or an extension that works. It will probably indicate which line you want to edit.
Now you can have similar expectations in the GUI and the console.