I was watching this video to get some ideas on what to play on an informal Christmas concert. From 0:21 to 0:56 the boy plays a song that sounds quite good. It looks like and Irish song , but I don't know the name. Does anybody know its name?
That's the old English carol "God Rest Ye Merry Gentlemen," one of my own personal favorites. This is a bluegrass version. It more commonly sounds faintly medieval, probably because of being written in the Aeolian mode (natural minor), where the seventh is a whole-step below the octave, rather than the more modern half-step.
The same mode is often found in Irish folk music.