Smartphones these days, even the lower spec ones, are capable of taking high resolution (though not always high quality) photos. That means those photos take up more space on the smartphone's storage. And when you have a measly 16 GB of internal memory, with no microSD card option, you will inevitably run out of space. That is precisely the point that Google is trying to make in a rare and admittedly amusing Google Photos video ad. And it is aiming its guns at, what else, the 16 GB iPhone.