Look at the picture again.
he has 3 fingers all pressed along the second fret. One finger on each of the three strings marked with a 2 on it.
His fingers are on an angle, because you just can't fit them in a straight line across the neck. But his index finger is on the D string, middle on the G and ring on the B. You can't see it well, but the E at the bottom is missed by all of them.
Don't worry, it's all a bit confusing at first, but once the penny drops it comes easier.
