So Posterous says this should be easy. Easier than with Blogger or WordPress or Dreamweaver or Drupal or any other common CMS.
Youtube embeds are easy enough.
[youtube http://www.youtube.com/watch?v=jISlelzxKyI]
JPGs, yeah.
Even native video files are probably relatively easy to upload, although having established a YouTube channel, why bother with anything else?
But let’s say I want to embed an MP3. Well, media tab over there says I can upload audio.
So it was just a matter of selecting the wav file. Presumably this will work for an MP3 as well.
Next: figure out how to get into the HTML.