The first instrument is a theremin and the second (can you guess?) is a Vulcan harp! Isn't that awesome? They are really rare, and people who know how to play them are even rarer. I so want to learn! I wonder what the odds are.... (Did any Star Trek fans just remember the royal fizbin? - see the 2nd to last video.)
This still seems to me like a strange thing for Spock to be doing,
but I haven't seen the episode so I don't know all the facts.
This clip was actually cut and edited by the uploader, but it
tells you what you need to know, and it's short.
Or maybe you remembered this clip about odds: