I am not an engineer. My mechanical prowess is maxed out by simple hand tools. But when I watched the video, I was immediately doubtful that the two halves of what might be called the combustion chambers could be made to seal in such a way as to keep all the hot, expanding gasses of combustion from escaping without doing much in the way of work.
It was an interesting video and, as Mikey said, using new ways to look at old problems is always to be encouraged. Let's just say that the devil is in the details and leave it at that.
