[Doubl]

I think most people get it that prize is twice as likely to be behind one of the two other doors rather than behind the door you pick. So one time out of three you'll get it right while two times out of three the presenter indirectly indicates the winning door.

Edit. Be nice if my downvoter would explain what's wrong with the above.

[icotyl]

This is probably the clearest explanation, sorry you were downvoted.

[Doubl]

Thank you! It's nice to know someone else feels that way.