Nope, not the Frosty The Snowman you think it is - this is from the youtube page:
Stylish 1950s UPA production design in this Christmas musical short features a rather Fred Astaire-ish Frosty and scads of Gerald McBoing Boing-style kiddies- plus a great vocal track of the seasonal pop standard. Chicago-area viewers were introduced to Frosty as he ran "over the hills of snow... jing-jing!"
This was the very first animated take on the classic holiday tune "Frosty the Snowman," pre-dating the Rankin-Bass TV special of the same name by 15 years.
Featuring a remixed version of the original song, this short aired regularly on Chicago's WGN-TV. It was broadcast on the station for many Christmases thereafter.