If he actually says, "I'm still alive" then this would imply Rob. However, since they found the camera, they would've found Rob, as he would've been pinned with the bridge rubble and/or had no reason to leave.
The secret is that there is no secret! We're all fooled by the guise of finding out such a deep mystery, that we are blinded by the truth of that which no such mystery exists to be discovered. Either that, or its a really damned good word search, I don't know. Good trance like music and it did have me boggled for some time (still does).
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