Finger-frame video mask: show another clip inside the frame made by your hands

Work on this yourself, without sub-agents.
Base video: {base_video}
Inner video: {inner_video}

The person in the base video forms a frame with the index finger and thumb of both hands. Build a moving four-point mask that follows that frame.
- Track four points: the tips of the left and right index fingers and the left and right thumbs.
- Connect them in this fixed order: left index → right index → right thumb → left thumb. Show the inner video only inside that quadrilateral; keep the base video outside.
- Move, scale and tilt the mask with the hands. Do not lock it to a rectangle — move the four points independently.
- Keep the inner video's aspect ratio and align its face position and size to the frame. Do not stretch the face when the mask deforms.
- Where tracking drops, interpolate. The edge must not jitter or lag behind the hands.
- Keep the edge crisp; only suppress aliasing.
- First render a 3-second preview for approval.
If the fingers cross into a bow-tie shape, reproduce it as is: never reorder the vertices even when the finger positions invert, and allow edges to cross.