A few questions:
What are the horizontal & vertical dimensions of your comp?
What are the horizontal & vertical dimensions of that footage?
Have you messed with the layer's scale in the comp?
Did you make the layer we see a 3D layer?
Did you create a camera and adjust it in any way?
View option are in the little pull down menu at the top right corner of the Composition window. Click there and select.
The pixel aspect ratio correction for the Composition window are at the bottom just to the right of the little tab that says 1 View. Click there to toggle.