Well, that's one of the things I meant.
If you look at debian-multimedia.org packages you'll see that flashplayer-mozilla is 9.0.151 in his stable repo. When I was playing with setting up Knoppix Flash worked fine. You also wouldn't get Firefox/Iceweasel 3 either. So far no one has gotten that to work on Knoppix. Just Iceweasel 2, and the Etch security repo would offer the latest version of that.
Although much was dist-upgraded to lenny in Knoppix, most of the multimedia is still from Etch. I think Klauss did that because he still loves xmms and upgrading the multimedia stuff to Lenny versions would require removing that. After all he still designs Knoppix to be his own personal Live Linux system. So he made xmms fit!
So some of the stuff may be old, but all usable. And there is no Live DVD with as much software pre-installed as Knoppix has.
I assume they'll be another new release this year sometime. If you want up to date stuff now though, I suppose one of the other distro Live versions would be preferable.
I played with adjusting the sources.list and aptitude dist-upgrade using a USB stick to save it all. It does bring it up to date for most things but breaks some things in the process. It really isn't meant for such total redesigning. Just installing a few things here and there is okay. I had installed the NVidia drivers (from Sid at the time) and so had full 3D and Compiz Fusion going on it. But upgrading multimedia would break Compiz. Just installing matching Etch versions of multimedia codecs and players from debian-multimedia.org worked fine though.