What do you guys make of this?

A comment from the video: The "coffins" shown in the video are grave liners. They are not owned by the govt but a company based in Covington Ga that manufactures them and has simply leased the land for storage.

Taken from wikipedia:

A Burial Liner, or Grave Liner is an enclosure that is placed over a coffin containing human remains, which is then buried in the ground. The casket serves as the inner enclosure of a deceased person; the liner serves as the outer enclosure. A burial liner is similar to a burial vault. The main difference between a burial vault and liner is that the liner only covers the top and sides of a casket, whereas a burial vault completely encloses a casket. In a burial liner, the bottom of the casket in this case is in direct contact with the ground. A burial liner serves to protect a casket during burial from being crushed and keeps the casket from being crushed when the heavy equipment that many modern cemeteries use pass over the grave. A liner helps keeps the ground over the grave is kept from sinking in, and helps keeps the ground even. Sunken graves can become a hazard: people can trip over sunken graves and can injure themselves in the process. For those reasons, many modern cemeteries require that either a burial liner or vault be used in burials. The use of burial liners is typical only in recent American history and is unheard of outside of the United States. The alternative to using a burial liner is to pile the earth up over the grave in order to allow for settling as is the practice in Europe and other parts of the world. For example, in the UK burial liners are never used because the inevitable subsidence of the earth over a grave is not viewed as a major problem: as the ground subsides over a number of years, earth is added to the depression to level it. Green cemeteries and some religions discourage the use of liners as they slow down the return of the body to the earth.

A very plausible concept on what these "coffins" could actually be.