The musician, Oen Kennedy, was playing his guitar and we stopped to listen. Isabella started dancing and clapping and laughing along. After this video, he started another song and it wasn't until he was some way through that we realized he was improvising as he went about Bella dancing and playing. At the end, he hinted that the CD he is recording now might have a bonus track inspired by the improvised song.
Of course we signed up for his mailing list!