The person who filmed this is the dog’s owner, I believe, and he encouraged his dog to walk towards the cats to provoke a reaction (and make an interesting video). Initially the dog wanted to back off. Nice video despite it being contrived.
Gang of cats get the better of a dog
Note: videos on this site are typically made by people other than me and held on YouTube servers or the servers of other businesses (not the server storing this website). Sometimes the videos are deleted at source which stops them working on this site. If that has happened I apologise but I have no control over it.