It turns out that it’s not all that easy to post YouTube videos to WordPress blogs by default. Basically, the editor screws up the embed codes.
Here’s a good solution: the Anarchy Media Player plugin for WordPress lets you link to the pages containing the file you want to embed and takes care of the rest. Load the plug into your plugins folder, edit the config file with the location of your blog, then you’re done. You’ll not see a Flash embed icon on your post edit toolbar. Click that, enter the link to YouTube or other popular online video sites, and you’re done. Pretty slick.