When manually attaching a video link (from YouTube, Vimeo, etc) to a post using the Facebook web interface, Facebook automatically recognizes the link as a video, and allows
Sharing as a link with /links instead of /feed seems to work better. YouTube, Vimeo, and Facebook videos are embedded as if posting manually.
curl -F 'access_token=...' \ -F 'message=Link to YouTube' \ -F 'link=http://www.youtube.com/watch?v=3aICB2mUu2k' \ https://graph.facebook.com/me/links