I've always loved that tree trunk (fake?) on top of the glass viewing area. It is something that adds an immersive quality to the exhibit, and it's a shame that more zoos don't follow suit.
I think that the sea otters are scoping out their human visitors on their own camera. Seriously though, I believe that the camera is located on the rocks at the back of the exhibit.
Melbourne has one over the glass at the gorilla exhibit although theres is more fake looking and goes unnoticed to most visitors.