That Prof Müller said it: Shock waves in addition of the usual things.
The picture in Your link is rather different from the thing shown
in the video, for the time being, I do not understand really what is
the new thing. From thermodynamics it is clear, that they (hope?)
to have a higher effective DeltaT, obviously without having
higher temperatures at machiney parts (which makes them expensive and/or short-lived)
I assume that those shock waves can be transformed into working pressure
without the high temperatures of the combustion shock wave touchng machine parts.
I hope we will hear more from Prof Müller in near future.
This link is somewhat more detailed and less press-release-silly.
in general it says what I surmised (by application of thermodynamics basics)