I never knew. This version is by the Four Preps. I doubt that the Welk family ever recorded or performed this song with lyrics.
As a piano lessons 50’s kid, I loved Welk’s “Calcutta” (still do, truth be told); my sheet music for the song had the same lyrics as the video you linked. The song has an interesting history, which I’ll try to find in a moment. There is a recording of fourteen-year-old Keith Emerson (in 1958) playing a song called “Nicola” - it’s exactly the same piece as “Calcutta.”
Well, that was easy.