# Source attribution and clip boundary

OpenAI — *Introducing ChatGPT Study Mode*, `XDYilxy1dn8`.
Official channel identifier: `UCXZCJLdBC09xxGZ6gcdrc6A`.
Publication date: July 29, 2025, from retained watch metadata; not newly refreshed.

```text
https://www.youtube.com/watch?v=XDYilxy1dn8
```

The selected research interval is frames [153,213), 60 frames at declared 30 fps.
The nominal absolute range is [5.1,7.1) seconds. Retained source-master hash:
`42dab89d7579b9e742a018291063b5e573bc3f3dbf61423e10e95c06543a9785`.
That master is not available here and was not rehashed or re-extracted.

The separate brief source clip is silent, 960×540, 60 frames, 30 fps CFR,
two seconds, hash
`f1fb70cfc2cdb68b93e9ee873fa71cb3fc7e5cc465188e3e3e41d7de0712d75e`.
Its library-relative path is
`evidence/study-keyword-double-underline/review02/source.mp4`.
It is not inside the editable ZIP and is not a production asset. The native
1920×1080 canvas and quantized 33/34 ms master starts must not be inferred from
this resized CFR derivative. See `source-clock.json` for all 60 clock mappings.

The replacement words, SVG folded surfaces, diagonal field, drafting marks and
filled emphasis paths are the existing library's original implementation, not
extracted source artwork. Geist is the licensed substitute font; retain its OFL
license. No source font, source equation, source logo or source frame is included
among the reusable assets.