Clear the free packets when hitting end of video

This fixes #393.  However, I found another instance of the same class of problem in Crisis Core (if you don't press anything and just let the intro video play.)  It's not caused by the same thing, not sure what it's expecting.

However, that was broken before, and this at least fixes Ys Seven (and hopefully Brandish.)  Didn't break the usual suspects which use mpegs either.

-[Unknown]