Thanks for the response. What happens (and has happened since the last post) is that the email goes to the postie mailbox with both photo and video attachments. The photos get posted fine, but the video simply doesn't show up.
Oddly, it does seem to be a piece of media that is attached to the post when I go to add it manually. So, when I know a video is being posted, I go into the post manually and insert the video shortcode for the video that is already attached (via postie) to the post.
Does that make sense? Would love any suggestions on how to fix it. If you want to take a look, let me know your email address and I can send you more info.
[ Please don't bump your topic. ]