It's all if-then statements, like "If this video has a bird in it, then show it to people who like birds." No ML needed /s
YTs algorithm now just seems to amplify very, very small fluctuations in view counts. 3 people just happened to watch the same video at the same time? It must be trending! Shove it in front of everyone. It’s like Google has used all of machine learning to recreate taking a derivative.