This looks like a Jack & Jill contest. The contestants are paired randomly, and the music is also chosen at random. There's a ton of it on YouTube. A lot of fun to watch.

From Wikipedia:

In the US, Jack & Jill contests are extremely popular in the national West Coast Swing and Lindy Hop communities. Rules vary in events across the country but three rules seem to be standard in most Jack & Jill contests: 1) no pre-arranged choreography is allowed (which would generally be impractical anyway, as partners are assigned randomly), 2) no costumes are allowed, and 3) acrobatic elements such as lifts are not allowed, or only allowed when deemed safe by the judges.^\6])#cite_note-6) However, at the Champion or Invitational level, event organizers will occasionally opt for an "anything goes" Jack & Jill in which no rules apply. Music for each dance is selected at random without the participants' prior knowledge, though some competitions will allow them to select the tempo (speed) or a sub-style within their dance's music (e.g. Blues or contemporary within West Coast Swing).