Trying to expand Document size before Render, not rendering correctly

I'm trying to export different elements of the scene as quicktime videos with alpha to comp in After Effects. Some shots require additional bleed room around the edges. The sollution should be going to modify-document and changing the stage size proportionally, while leaving scale content unchecked, and anchor set to the middle. 

After rendering, the first frame jumps to a random location, and the following animation is offset in a way that is different form the original shot. There is a camera in the scenes, so I'm not sure if that's the culprit.

Any ideas how to resolve this or take another approach to add bleed room around the render would be much appreciated.