Codec packs are often a source of trouble, but if it worked for you, why not?
> Maybe you should've tried to install a newer / another version of ffdshow to fix your problem. The x264.nl version works fine here, as do the builds from Free-Codecs and CCCP-project.
You can also have a look at this utility for trouble shooting:
http://www.google.com/search?q=matroskadiag