Pinch & zoom!
You need to clear the text/buttons by tapping on the cam player before you can Pinch & Zoom.
For a dynamic video, we play the clip and use a Screen Recorder to zoom & navigate the frame, touching/dragging your finger to follow your path.
Download & crop
The iOS Photos app has some easy tools to crop and trim clips to your ride.
Download the clip from the Sessions tab in the iOS app, and then make edits through your camera roll.