YouTube seems to have changed their back end again, so downloads might not be working. We should have this fixed in the next day or so for the 2.0 branch and will put some download links up when it’s ready.
For Miro 1.2.8 users, you’re going to need to update to 2.0 to get this fix — sorry for the wait.
This might be the excuse we need to flesh out the plugin system we’ve been wanting to build. Then we could keep users updated without needing to re-release the entire application (and anyone else could build add-ons too, which would be amazing).
http://www.getmiro.com/blog/2009/01/youtube-download-issue/