I’m not sure if this is the same problem, as I’m not embedding YouTube code specifically, but just some object/embed tags.
In any case, when I publish, the object/embed tags don’t seem to end up in the right place in HTML. They appear outside the “entry” div and because of this they seem to hose the rest of the page’s CSS.
Is this a bug, or a feature? Either way, is there some way to work around it? Embedding iframe tags seems to work as expected.