https://mobile.twitter.com/danbri/status/1545760855052193792
The reason - they quoted a small Richard Feynman clip from an archive BBC show. After fixing it took 12 more hours to unblock the video.
https://www.youtube.com/watch?v=axuGfh4UR9Q
Way to go BBC, protect your rights, make sure nobody cites any of your precious videos. /s