From the website:
Every week, we invite an artist or a band to play in the streets, in a bar, a park, or even in a flat or in an elevator, and we film the whole session. Of course, what makes the beauty of it is all the little incidents, hesitations, and crazy stuff happening unexpectingly. Besides, we do not edit the videos so they look perfectly flawless, instead we keep the raw sound of the surroundings. Our goal is to try and capture instants, film the music just like it happens, without preparation, without tricks. Spontaneity is the keyword.
Some of the notable appearances have been from Beirut, Sufjan Stevens, Jose Gonzales, Fleet Foxes, The Shins... whoever picks them has fine taste.
Here's the website
and here's their YouTube channel