Here's my theory about last night
So now we know for sure Henry is an Other. It makes perfect sense he would help Locke because he needed to keep up the charade. But then his brilliant plan came unraveled because Sayid is just too good. But, I don't think Henry knew how to put the doors up. My theory is that the alarm and countdown woman's voice and the doors closing was supposed to be a signal that Dharma people were making a drop (meaning the food Kate and Jack found when they ran into Sayid, Ana and Charlie). Of course Locke didn't know what it meant because Desmond wasn't there to tell him and never told anyone this would happen, and Henry couldn't say anything because he was really an Other. Henry knew why the doors came down, but, the doors went back up because the drop was done, not because Henry did anything.
