Errr ... they are knitting to Heavy Metal Music!
More information about its origins is here - and remember that Finland also has World Championship Wife-Carrying and lots of Air Guitar festivals! They have long dark nights in winter there ...
Young lady being interviewed at 0:14 is my daughter, who was a Competitor in the World Championship Final! She had a fabulous time and said it was so much fun, everyone very friendly, all accepting that knitting to Heavy Metal music is so bonkers ... it's brilliant!
Incidentally, the lady competitor, in the black and red outfit also comes from Edinburgh and, if you look closely, you will see that her outfit is made from recycled bike tyres!