I am a Mechanical Engineer (retired).
In one part of my life I was a Marine Engineer Officer. The ships I sailed had Burmeister & Wayne 2 stroke Diesels with three pistons per cylnder, one main piston in the centre and two "Valve" pistons above and below.
The new engine this man is describing is a variation on this design, he has moved both the valve pistons to the top of the engine. He himself says this new engine can't be patented, the reason why is because this is not a new concept.