but with three options for water source why did they pick the one pointing towards the van? They could have tapped either of the other two outlets to get their source of water.
Can't tell for sure in this picture, but most hydrant adapters aka "water thief" have smaller discharges on the side, the main one being the "straight through" connection. Changing direction in the flow can cause a serious drop in supply, depending on how much water you are flowing (little flow = little drop, large flow = large drop).
When we determine the amount of water needed at a fire it is based on what we "might" need, not what we actually need.
If your hydrant is rated to flow 1500 gpm then you need to use the adapter that will maximize the rated flow, so you use the big hole.
This particular fire had heavy fire showing upon arrival with an exposure problem (house next door)
http://www.phillyfirenews.com/content/firewire/detail/2173/