I get the PHP error
Notice: Undefined index: list in /Applications/XAMPP/xamppfiles/htdocs/wp-content/plugins/jetpack/modules/shortcodes/youtube.php on line 152
above every YouTube video embedded in a post.
It's a subdomain multisite install with multiple instances of jetpack, and as you can see it's run by XAMPP for Mac, using PHP 5.3.1. WordPress version 3.4.1. None of the other multisite sites have YouTube videos embedded by jetpack.