I put together a little script demonstrating how to install and use various video codecs and use them in a test application (media player classic). To try it out, do wget http://kegel.com/wine/winetricks wget http://kegel.com/wine/codecdemo sh codecdemo (after of course reading both scripts to make sure they don't do something evil.)
To make this demo script easier to write, I added quicktime72 and mpc verbs to winetricks. (I also added a vlc verb, but that wasn't so useful as a system codec test, since vlc has its own embedded codecs, and doesn't use the system's.)
The demo shows that Quicktime works more or less, but .wmv doesn't work (even with the codecs); it probably needs either native quartz.dll or Maarten's VMR9 implementation (which he is busily finishing up now; it seems to be good at finding video card driver bugs).
Next step: Dirac.