Good eye.  I haven't wrote a custom route in a while.

```
  match '/media_objects/:media_object_id/section/:id/embed' => 'master_files#embed'
```
We're accessing embed through media objet and section because it's the base permalink that is saved.  We can't append to a permalinked URL that doesn't exist.  Does that make sense?

Normally :media_object_id would  be :id, but I had to change it so it doesn't conflict with the :id that we need to use in the master_files#embed action. Of course I'm thinking now we could change master_files#embed to check for :id and :master_file_id.