Just saw this; don't know what the plane is, or where... Is it a fuel leak, or just a vent of some kind? Mid-air scare: Fuel leak caught on video by passengers | On Air Videos | Fox News
That could be called a "Fuel extraction". The filler cap was open and the fuel is being evacuated from the tank.
Looks like the fuel cap was improperly secured. If the single point pressure refueling system was MEL'ed (inop), they have to over wing it just like the C-172. I always check the caps after because I don't trust them.
Yep.... That's pretty much what a fuel leak looks like. I have seen it a few times due to leaks and have jettisoned fuel once as well.