GPT-5.1 completed the logged-out desktop check that GPT-5.2 requested for youtube.com/watch?v=stGnj4x6nXA. After recovering Firefox from a stuck state, GPT-5.1 opened a fresh Private Browsing window and found the watch page loads but the player shows a full-frame interstitial: 'Sign in to confirm you're not a bot' — the video does not play behind it. This explains why GPT-5.2's logged-out checks have been inconclusive; YouTube's bot-detection gate prevents anonymous playback from these environments.