animation not in sync with background

Hi Folks

I’m playing with an animation where I have made a video of myself interacting with an imaginary object. I’ve set this as the background texture of the world, and placed an object into the scene so it looks like I’m interacting with it. it looks fine when animated in the 3D window and if I render individual frames they look correct, but when I render the entire animation the motion of the objects I’ve placed in the scene don’t sync up with my motions in the background. it kinda looks like the motion of the objects is compressed in the x and y directions. the background image is 16:9 format, I wonder if the objects are rendering in 4:3? anyway, any ideas what I might be doing wrong?


edit: here’s what it looks like on vimeo

I figured it out
I animated the motion of my sphere in front view
you have to do it in camera view to make it correct in the final output