Short version: just type "automp" instead of "mplayer" everytime you want to start mplayer and get awesome features like automatically skipping a few seconds at the beginning (this is great for skipping that aweful intro of that awesome TV show you like so much!) or custom keybindings depending on the file name!
Long version? Read the README at GitHub!
Example configuration file:
# Additional options for mplayer
# Bind space to `seek 10.00`