"404 Not Found" after clicking "Watch in Browser - mp4"

[holta]

Video that IIAB Calibre-Web appeared to download correctly:

"Amadou & Mariam (feat. Manu Chao) - Sénégal Fast Food (Official Music Video)"
https://www.youtube.com/watch?v=J43T8rEOg-I

Unfortunately however, when clicking on http://192.168.0.108/books/book/2 -> "Watch in Browser - mp4", the resulting page (http://192.168.0.108/books/read/2/mp4) immediately fails, showing "404 Not Found".

iiab-diagnostics: https://paste.centos.org/view/c950f6f0

root@box:/library/calibre-web# tree --du -h
[ 34M]  .
├── [ 14M]  Amadou
│   └── [ 14M]  Amadou & Mariam (feat. Manu Chao) - Sénégal Fast Food (Official Music Video) (2)
│       ├── [ 14M]  Amadou & Mariam (feat. Manu Chao) - Séné - Amadou.mp4
│       └── [110K]  cover.jpg
├── [ 19M]  chevy
│   └── [ 19M]  Ryce & Chevy - everyday (live band in a van version 🚙✨) (1)
│       ├── [ 19M]  Ryce & Chevy - everyday (live band in a va - chevy.mp4
│       └── [ 82K]  cover.jpg
├── [128K]  config
│   └── [124K]  app.db
├── [348K]  metadata.db
├── [ 13K]  metadata_db_prefs_backup.json
└── [276K]  xklb-metadata.db

Tangentially related:

• "504 Gateway Time-out" when clicking "Watch in Browser - mp4" #319