This happened in CS5, CS5.5 and now in CS 6.0.3 also. When I'm using the Lens Distortion filter(also with Shadows & Highlights, Change Color) there are some random frames rendered with an artifact like this. It's only one frame once in a while, but it renders the video useless.
I tried alternating the filters (Lens Distortion filter first, in the middle, or last), but from what I could see it's random. For example, that clip doesn't have Change Color. The problem occurs in the rendered preview and in the final export, even with Use Previews OFF and Maximum Render Quality. The strange thing is that it occurs in different frames than those on the previews. If I click on Export Screenshot the artefact won't show. I can't understand what is happening. Also, I can't affort to disable CUDA rendering.
Most recent video drivers, SLI GTX570 configuration, but happened when I used a Radeon HD4850 too.
Shadow/Highlight has caused some grief. Try another effect instead. Does the issue still occur?