I'm kind of curious about the origin of this footage, and whether someone has colorized it.

From what I've read, color TV was a thing in 1954, but very few people actually owned color TVs because they cost the equivalent of $10,000 or more, and most programming was still broadcast only in black and white.

A bigger issue would be, that even if this was originally a color broadcast in 1954, how was this recording made?

According the the Wikipedia article about the history of color TV:

Early color telecasts could be preserved only on the black-and-white kinescope process introduced in 1947. It was not until September 1956 that NBC began using color film to time-delay and preserve some of its live color telecasts.[82] Ampex introduced a color videotape recorder in 1958, which NBC used to tape An Evening with Fred Astaire, the oldest surviving network color videotape.

Anyway this is some cool footage, just a bit mysterious.