Surgeons manually helping that baby to get free from its amniotic sac!
The amniotic sac is an opaque bubble that covers all babies in the womb from right after conception. As the baby grows, it fills with fluid, amniotic fluid. The sac cushions the baby from bumps, protects the fetus from damage and allows the fetus to move freely.
It is rare for a baby to be born with the sac still completely intact as most sacs split open during labour on their own, releasing its protective fluid. This is what people mean when they refer to a mother's waters breaking. In some situations like the one presented above, if rupture of the membrane doesn't take place and the fetus is born within an intact sac, the sac is broken by the doctor either when a woman is ready to give birth or right after delivery.