The ramifications of "bending" a law to punish this guy makes for interesting debate, but as I see it, it's wrong. I've been doused that way a few times... by accident and on purpose. When you're eight and are already soaked, yes, it's fun, but at any other point in life it's not so amusing.
Believe me, there's a big difference between showing up at work or school a little wet from the rain, and showing up covered from head to toe, soaked thru your underwear, in gutter-filth. Leaves, trash, dirt, motor oil, excrement maybe... it ain't just water.
On the other hand, sometimes it can't be helped (although in this clip it looks intentional to me)... so it pays to be very careful where you walk or stand along a road on a rainy day.