I am actually curious myself about the rubbing alcohol in the container as it is something my parents did in their '19 Pilot during an xmas trip from Texas to Minnesota and my mom commented on the potent smell of the rubbing alcohol when they washed the windscreen, but it apparently worked. Wish I had known the trick before I did the below.
I took the trip from Georgia to Minnesota and my mediocre MB dealership neither had the Winterfit concentrate and my service advisor told me they only stock in service what is appropriate for the climate in Atlanta. Ended up draining the massive washer tank via thoroughly washing the windshield in a back corner of a gas station parking lot and refilling with the -30 degree stuff you can pick up only in northern states, that was a chore as the MB tanks hold well over a gallon of fluid and the washer pump automatically stops after like 10 seconds.