Getting pixelation when I add a camera layer to my imported .mov. Even more pixelation when rendere

I've created a composition with animation in After Effects.  Because of the complexity of the composition and its many layers, adding a 3D camera layer to it spawned a whole lot of issues with the wipe effects I had on the pre-existing layers and movement of my layers.  So I rendered the composition without the camera layer, nested the .mov into a new comp and added a camera layer.  The animation works great but I'm getting a lot of pixelation.  Highest HD settings, full resolution, preserving quality of layers when nesting and not sure what's happening.  Any ideas?  Thanks!