I have exactly the same problem.
I can not download ghosts in time trial, I have a message that says: "you can not download ghost laps because you do not have online access privileges"
Now, I do not know how to get the privileges.
Perhaps someone with ideas?
All my setting where everyone, so what i did was set it to friends only, log out of live, go back into live, reset it back to everyone, logged out, then back in, and bingo it now downloads ghost laps. Almost as if it doesn't register the settings at first, and it needs to re save them to your profile or something.