On PC and even console, I have seen that when mobs come to an edge of a platform or even randomly, the mob would spin aggressively in circles. This seems to happen on every version of newer Minecraft and although not being a major bug, I feel like it's pretty annoying seeing a lot of mobs just randomly spinning. Here is a clip on youtube I have found which shows what happens: https://www.youtube.com/watch?v=DN4O1fvREko
Environment
This seems to happen on PC V 1.14.2 and the newest versions on console.
Are the mobs that are spinning inside of water?
The video you linked is very old and therefore of a very old version of Minecraft that is no longer supported.