Well, in conclusion, it would seem most think these jacks are dangerous and may work for some applications, but you better have jack stands under whatever you are lifting and a quick arm if the bag pops while putting the stands under the car.
My experience with a hydraulic jack is it won't lift if it has a broken a seal and if it breaks a seal under load, it will either not jack past a certain weight or just start leaking, slowly....
Thanks everyone for the input! I will NOT be buying one of these.