If you have a text layer on the Video timeline in PS CS6, there is an option to use keyframes with Text Warp. Unfortunately, unlike other keyframed animations, the change from one warp state to another is not gradual. It simply jumps from one warp selection at one keyframe to another warp selection at the next keyframe. Converting it to a Smart Object removes the Warp Text animation option but retains the animation.
Is this behavior by design?
It probably is.Time to move on to After Effects...