De-Icing a plane

Got delayed in Boston Logan airport because major snow storms caused a ground stop in Philly, where I am supposed to connect to SC. The ground stop was lifted but before we could move, they said they had to de-ice the plane. I always thought de-icing entailed some giant ice-scraper going over the surface of the plane, but instead, it's this:

It appears they spray de-icing liquid over the entire plane:

I guess that's a lot easier than using a giant ice-scraper.