Obviously, the anemometer on the top of the Falkner Beacon did record 50 knot winds that day, but the wind in those videos is, also very obviously, far less than that. There is NO WAY those sailors would hold those sails in even very brief gusts to 50 knots.
From the water state, waves and spray, and the size of the sails used, my guess would be around 25-30 knots. It may be gusting breifly into the mid to high 30's.
Do not discount that though. Sailing on the open bay in winds around 30 -35 knots IS extreme!