So, I know this looks bad from a human perspective, but if you look at it from an antelope perspective this is the most correct choice.

In humans, if a parent dies protecting a child there is a chance there is another parent to raise the child to adulthood. Even if not, there are care takers and programs that give the child the chance to survive until adulthood.

However, to the antelope, if the mother passes, the baby will most certainly be doomed to die anyway. There will be no other care taker to provide milk for the baby. If it doesn't get eaten first, it will starve to death. The mother can easily have another baby next year, but both will die if mother dies now. The mother can't even stay and try to fight. It has NO chance in a physical confrontation with a leopard. The leopard would gladly take an adult antelope over a baby if it can easily catch it. Again, which would lead to the baby's death also.

So for the antelope, the best survival strategy is to abandon the baby and to try again next year.

Now let's discuss why the camera men don't try to "help out". Because in nature this is just how the predator eats. Would you still want them to intervene if you knew the result would be the Leopard would die of starvation? During the dry season that could definitely be the result. Or what if this is a mother leopard and this baby is going to feed her cubs. If you save this baby you may actually be killing all the baby cubs.

So hope that helps explain the situation to those that are not familiar with this sort of thing.