Okay, here we go

Download, remove the ".txt" from the end, drop it in /usr/bin and chmod +x it

This script when called by mplayer-opt <FILENAME> will read the size of the video and choose the appropriate low-res for it. It will then echo what resolution it chose and then call mplayer with the the optomized flags (-hardframedrop -noslices etc).

It's a work in progress and I plan on adding options to it and maybe some better optomizations if I can find them. It's also my first shell script ever so any feedback/corrections/suggestions are more than welcome!

EDIT: UPDATE AVAILABLE, SCROLL DOWN