Adding it will most probably not possible, because of:

* too much space for mplayer & libraries dependencies needed
* mplayer has no official debian packet
* mplayer is not really "free"

Don't missunderstood me, I'm an mplayer fan, but knoppix is redistributable and shall remain it.

But I'm working on a solution to add mplayer on-the-fly from the internet/directory, while knoppix is running ...

And I for myself have succeeded in doing so ...

cu

Fabian