For every one unit your camera moves, the UVWarp modifier moves your texture one texture width. To make your texture move like it’s fixed to your camera make your texture one unit wide in the 3d view.
Quick (but not exact) instructions to do this:
- Scale your ‘test’ object by 1.21.
- Apply scale (the UVWarp modifier doesn’t seem to respect an objects scale).
If you want the texture to fit inside the camera then also change the ‘Orthographic Scale’ of the camera to 1.0.