How did Umbridge know?

[mrs_sonofgib]

No: HPFGUIDX 112872

theotokos wrote:
{snippety, snip, snip...)
>      Dumbledore now swooped down upon one of the fragile silver 
> instruments whose function Harry had never known, carried it over to 
> his desk, sat down facing them again, and tapped it gently with the 
> tip of his wand.  
[snip]
> What is that about?  It must be giving DD some sort of answers 
> about Harry's vision.  Essence divided?  two snakes?  Does it have 
> something to do with LV possession of Harry?
  


I've always thought that was revealing that Voldemort had been 
possessing the snake (they were one but are, in essence, divided).  
Snape does tell Harry during an Occlumency lesson that Harry was 
seeing through the snake's eyes because that is where LV was at the 
time...
Was my understanding over-simplified again?
~tina