i think he was prolly just showing off for the camara, and didnt understand that he couldnt drive like that, prolly someone who doesnt know anything about cars, and figured its an off road truck lets drive in the sand and water.
i think by the way it happened toward the camera, i think the guy was surfing and taping and they were leaving and thought hey its wet, go over there and tape me doing a power slide . . . . . thus he tried to get his tail end fishtailing to powerslide towards the camera not thinking about the sand gripping on his tire, and therefore flipping. because if you think about it, it would have looked cool if he didnt flip and just did a massive powerslide. Thats just my take since i have the mind of a stunt devil teen