Some flashmobs are plain underwhelming. But this is one of the good ones!
If the definition of a flashmob (from Wikipedia) is:
‘a group of people who assemble suddenly in a public place, perform an unusual and seemingly pointless act for a brief time, then quickly disperse, often for the purposes of entertainment, satire, and artistic expression’
then this group does a great job of entertaining passers-by in a narrow shopping arcade in Asakusa, Tokyo. More than 200 people end up joining the dance. It’s worth watching to the end.