That deer has a right to be scared! Look a little closer and it becomes apparent that the squirrel is actually one of those carnivorous vampire flying squirrels!!!!
I saw my first flying squirrel while camping down at Lake Monroe last year. I was trying to break a branch up against the side of a hollow tree and felt something wet landing on my head. When I looked up, I saw the little bugger that had just peed on me! They are cute little things (despite their bathroom habits)!