docs(badapple): record where hd60.mp4 came from

bad-apple/README.md

@@ -13,6 +13,23 @@ Design: [`../docs/superpowers/specs/2026-10-31-bad-apple-vector-design.md`](../d
 Plan: [`../docs/superpowers/plans/2026-11-01-bad-apple-vector.md`](../docs/superpowers/plans/2026-11-01-bad-apple-vector.md)
 Measurements and gaps: [`REPORT.md`](REPORT.md)
 
+## Source video
+
+`hd60.mp4` was **downloaded by the agent** in the earlier OpenCode session
+**“Bad Apple demo tool”** (`ses_e6d6b504dffeIRKLu3RqZAiFRp`, message seq 641),
+not supplied by the user. The design doc's “human-supplied” wording is
+inaccurate.
+
+- Item page: <https://archive.org/details/hd-60-fps-bad-apple-shadow-art-pv-720-x-960-60fps>
+- Direct file: <https://archive.org/download/hd-60-fps-bad-apple-shadow-art-pv-720-x-960-60fps/_HD_60FPS_%20Bad%20Apple%21%21%20_Shadow%20Art%20PV_%20%28%20720%20X%20960%2060fps%20%29.mp4>
+- The fetch command was `curl -sL -o hd60.mp4 "<direct file>"`.
+- Measured: **34,903,925 bytes**, **960×720**, **60 fps**, **219.521451 s**,
+  h264 / yuv420p, AAC stereo.
+- Local path used by this demo: `/tmp/opencode/badapple-real/hd60.mp4`.
+
+The archive.org item name is scrambled (`720-x-960`); the file inside is
+960×720, 4:3.
+
 ## Quick start — current MAME demo
 
 From the repository root: