I'm glad someone did finally stop. That really pissed me off watching those other boats go by, It occurs that hypothermia could also have got them too.
Once you've been in a flipped truck off the highway and watch all the jack-wagons drive by while you kick out the windshield (I wasn't the driver), you lose what little faith you have in people.
The gents who made the video commented that a lot of boats turned around to help, it just wasn't so obvious in the video. Also said they'll be making another video with further details on the crash.