EDIT: Corrected LNG to CNG Compressed, not Liquified
The video guy is a little confused. Hydrogen fuel cells and tanks holding hydrogen to burn are two completely different things. At one point he says that, then he confuses the two several places.
Regarding the burning of hydrogen, sure it's clean, and you can do it with a normal internal combustion engine. Really don't need to develop a special engine to do so. It does appear that Cummins is working on a hydrogen engine specific to semi trucks.
I think the more interesting thing is that they are developing an engine that shares a common block, but can be built with different heads and intakes, to burn diesel or gas or other fuels.
Hydrogen, propane, or liquified natural gas, all burn very clean. The problem always has been and will be, two fold. Tanks and refilling.
It takes high pressure tanks for propane, and extremely high pressure tanks for H2 and CNG. That means weight, space, and safety concerns.
Then the problem becomes refilling. There is one CNG terminal in Amarillo, I have no idea where there is another. Propane is pretty common, but mainly for 5 gallon bottles. And as the video says, the only H2 stations are in California.
Hydrogen adds another problem. If you're not making it by refining fossil fuels, you make it by electric hydrolysis of water.
Our electric grid is at capacity now. Are we going to add millions of electric cars, and thousands of H2 plants?
It will only be possible if we start building nuclear power plants again.