I take it that something has happened to Tennessee and Walter (David), now that Daniel's is alone and relying on Muthur to give her locations on the Alien. In previously released footage, she was with Tennessee and relying on Walter for directions. Personally, I think it is David impersonating Walter. Maybe David tried to lead her into a deathtrap and she survived, and she's now relying on Muthur for information. I think the images we have seen of David trying to teach Walter things is actually being done for 1 reason, but by 1 of 2 methods.
1. To learn as much as possible about Walter, in order to make it easier for David to impersonate him.
2. To make Walter similar to David in action and thought, to more easily impersonate him.
I think great effort will be put into making the audience believe that it is indeed Walter; probably going all the way to the end, with the truth most likely being revealed post-credits, maybe with Walter (David) casting some triumphant smirk once Daniels is dead or back in cryo. Maybe David will head to the bridge and set coordinates for somewhere worse. Surely they wouldn't wait for the next film to reveal it was David afterall? It would be wild and unexpected though.
On a side note, the room she's in with the alien really reminded me of Isolation, which is wonderful.