Round 2: dark to light
Dawn breaking: "Alpine ridge: dark to full sunlit peaks" is the one: a real, slow dark-to-light arc over mountains, 4K, no flare. Play it once and hold on the lit peaks. Runner-up: "Dark countryside slowly into dawn" (gentler, flatter). The dusk mountain is shown played backwards, which turns a sunset into a dawn.
Eclipse: no free clip shows a landscape going dark at totality and the light returning; those exist only as photographers' copyrighted work. Closest free options: the three here (partial eclipses, no return of light), or ESA's 2017 totality timelapse through a telescope: the sun goes dark, the corona appears, the "diamond ring" brings the light back. Licence CC BY-SA 3.0 IGO (credit ESA/CESAR), and the music must be removed. Watch on ESA.
Claude's picks, round 1
First light: "Blue hour, a thin orange horizon" is a real night-to-dawn arc. Its last third has a sun flare, so trim it and play it once, holding on the last frame like the Dawn frame, rather than looping. For a calm loop: "Blue hour over mountains and cloud valleys" or "Fog and dark ridges, warm horizon".
Seeds: "A seed head against the sun over hills": the seeds actually blow away. It is the strongest metaphor, but the subject sits where the text goes, so it needs text set left or low.
Birds: "A flock crossing a golden sky" (movement), or "Birds across a pale gold sky" (very quiet, easy to read over).
How to use
Click a clip to play it behind the opening line. Previews stream from Pexels at low resolution; nothing is downloaded. All are on the Pexels licence: free, no attribution needed. Brief: video-brief.md.