YouTube returns flaky per-client responses: the web clients intermittently mislabel normal
videos as 'DRM protected' (like tv did), and android_vr can get bot-flagged under heavy load.
Neither client alone is reliable. So:
- PRIMARY player client = android_vr: high-quality DASH (399+251), no PO token / Deno needed,
reliable for normal use
- on a bot/DRM/format failure the worker retries with the FALLBACK set (web_safari,web,android
+ POT sidecar + Deno) — bypasses bot-detection when android_vr is flagged
- both client sets admin-tunable (DOWNLOAD_PLAYER_CLIENTS[_FALLBACK])
Verified: the previously DRM-failing video now downloads steadily via android_vr, no DRM error.