I built a 75.5 s, 1920 × 1080 product explainer for a placeholder analytics product from 10 storyboard frames (288 named layers). Layers that share a name between frames are matched and animated by what changed (enter, exit, move, resize, recolor, retext): 430 changes across 9 transitions, timed from brand motion tokens. Inside the frames, 100 motion beats written into the same storyboard (a slow camera push, counters, growing bars, staggered lists, live tickers, data flowing into a hub, a cursor that hovers, clicks and flips a pricing toggle) keep the picture moving: measured on the 1813 rendered frames, 2.1% are identical to the frame before and the longest still stretch is 0.33 s. A brand check covers palette, type scale, radii, motion tokens, approved messaging and layer collisions: v1 fails with 1 off-message headline, v2 has 0 issues. Three creative-team feedback notes are applied as revisions (longer pricing hold, chart growth slowed from 0.95 s to 1.20 s, approved closing line), taking the cut from 72.88 s to 75.53 s. A second 3-frame storyboard compiles through the same code unchanged.