I've replayed this 5 or 6 times now and I think Walt is saying "I have to tell you...the others", but I'm not 100% sure. His lips didn't move tho, which makes me think he is either projecting an image of himself or she is having a telepathic moment thanks to their connection with Vincent. I thought I also heard "kill Shannon" in the whispers just before she saw Walt.

oooh I couldn't quite hear what he was saying... but the psychic connection b/c of Vincent makes sense

Somebody worked this out .

Walt was talking backwards. What he said, when reversed, was the following: "Press the button. No button's bad."

Actually when played backword, what he says is "Don't press the button. The buttons bad."

My wife and I clearly heard him say "I have something to tell you". It's good to have a center channel sometimes. :)

We didn't bother to play it backwards or anagram it, though.

You guys are awesome. I just thought he said something about Vincent.

I didn't know what to think about that. I kept thinking "wasn't Walt in a life jacket?" and I barely even heard the whispers. That part just made me confused even though I understood she would see someone and no one would believe her.