Turn short-1.mp4 into a new vertical short video short-1-v5.mp4:

1. Shrink my talking-head into a circular picture-in-picture in the bottom-right corner, clear enough to see me speaking, without blocking the subtitles.
2. Swap the main screen for an animated B-roll that follows what I'm saying: when I mention a concept, the visuals draw that concept. Style light and fun, line-drawing animation is fine, no need for realism.
3. Keep the original audio, original subtitles, and duration unchanged.