There was an article earlier on HN (http://news.ycombinator.com/item?id=1361442 http://news.ycombinator.com/item?id=1361442) that talked about there still being

There was an article earlier on HN (http://news.ycombinator.com/item?id=1361442 http://news.ycombinator.com/item?id=1361442) that talked about there still being patent concerns with the new codec and so it seems like Microsoft may wanting to avoid being named in any potential suits by requiring the end user to install the codec rather than providing it by default.