Mats has just posted several videos of simultaneous baritone ukulele and keyboard. I am surprised at the amount of volume he gets out of the bari using only his left hand but it looks like he has the microphone quite close to the bari-uke. He gets a quality production in all of his videos. He is from Eskilstuna, Sweden which is about two hours West of Stockholm.
Mats Öljare plays a tune from Phantasy Star II, and the ending of Soul Blazer.
Mats site is here and he experiments with various instruments including a fretless painted plastic balalaika. If you are interested in experimental music be sure to check out some of his other videos. He even has a short treatise on the balalaika and plays a nice quality one from 1980's Moscow. I also have a balalaika with nylon ukulele strings and I have tuned it C-E-A unfortunately the neck is not straight and so playing above the 5th fret is problematic.