(Note: I split this from the
Koma why so cool thread)
These tops are called Zuguri Koma. I found an announcement for the 27th (!) national ("all-Japan") contest next February in the town of Tsugaru, in the north of the main island:
link. From the photos there it must be the same place where those videos where filmed.
I need to get a Zurugi snow top for my collection, although I won't be able to properly test it in San Antonio