@bandagentileza on Twitter sent me a link to a video of his band. The guitar on the right is a handmade ukulele (looks to be a cigar box style). Anyway, Mercury Duo is the name of the band, and they are great! Guessing from the link, I think they are possibly from Brazil? "O Sen Sen Sen" is a fun (and yet deceptively complicated) song. It reminds me of music that you might hear in a more recent Mario Brothers video game. You know, when they started to step up the music a little bit. Anyway, I really liked watching/listening to it... in fact... I'm going back for more now.