Post Formats without a title 404 and don't post.
|Reported by:||Ipstenu||Owned by:|
Reported by noumaan in the forums: http://wordpress.org/support/topic/video-post-format-must-have-a-title?replies=2
If you make a Video Post with no content, and only add in the video to the embed box, WordPress can't generate a title so the page comes up with a 404. This also happens on Image and Audio posts.
Once you add a title, you can't remove it. Obviously the post needs 'some' title, but it's failing to auto-gen without content.