The video shows a man transporting a fish from a bucket of nice fish-friendly water to a container filled with an unspecified substance (we know it's not liquid nitrogen, as the temperature is shown at -35 in the beginning, which is too warm for nitrogen to still be in liquid form, no matter the unit).
A subduction zone is formed at a convergent plate boundary when one or both of the tectonic plates is composed of oceanic crust. The denser plate, made of oceanic crust, is subducted underneath the less dense plate, which can be either continental or oceanic crust.
The trench formed by these two oceanic plates is the deepest spot in the world's oceans and includes the Challenger Deep. Oceanic trench begins to subduct. Ocean trenches form when a heavier and flexible oceanic plate begins its decent.