In that clip she spends some time describing where you can see the shower from in the bedroom, hallway, and closet also - curiouser and curiouser.
I have nothing to suggest this thought,
but I can see Travis sitting down in the shower when he discovers she is taking the pictures (maybe even banging the back of his head against the shower wall in his frustration with her). The shower door is closed on the face shot but open on the torso one that follows. I believe
that one probably was "inadvertent" as Jodi says. She didn't have a chance to put the camera down before she started in on him (most likely with the knife). Then the ceiling shot which comes many seconds later is when the camera has been tossed in the struggle.
I have another awful thought that when Travis saw she had a knife, he turned his back to her on purpose. In his blog he talks about doing that with his mother as a way to deflect her blows and so they won't hurt so much.