I am extremely skeptical that the internal pressure of a housing closed at sea level and then flown to 6000 ft would have enough delta P to blow off the dome. Does that mean if I drive to Denver with a sealed housing, my dome port will fall off? that seems like a really really bad design if that is true.
So in general I think that screen caps are never quite as crisp as dedicated stills, but neither will get you photos from even the most simple dedicated camera. Playing around with the pic of the turtle gets some nice results.