There is no coordination required at all. Where are you from. They are playing in unison, so it is very easy to follow each other. In a normal band of any genre, each musician is playing a different part while keeping a similar theme. That requires skill and practice. That is why some bands need conductors. In that video a conductor would be redundant
Thanks a lot for the clarification -- I always wondered about the name! It is pretty widely known in Irish trad circles as "Kerfunken", and I notice that there are versions with either or both spellings on line. Have a great day!