Three ways to
shoot a circle
Every control sits inside the right thumb's arc: no reaching for the top corners, no second hand. Grant the camera and each phone records for real, with playback and approve. Press and hold to feel the difference.
What is identical
Circle viewfinder, lime arc as the 60 second budget, front camera by default, preview before anything sends. Only the grip changes.
Reach the constraint
On a 6.1″ phone the right thumb sweeps a ~180 px radius from the bottom right. Flip, flash and cancel all live inside it here; the top corners stay empty on purpose.
Try to break it
Start a take and cancel mid-way. Flip the camera while recording. Lock and walk away. The take only leaves after you tap Send.
On playback
With camera access the preview is your real take, looping muted, exactly as the crew would receive it. Retake discards it on device.