Took me while but I got it
in kevmo-world
watt - unit of energy or power, as needed. A 1 MW burst of power for 1 nanosecond can power a thousand houses in perpetuity. We are saved!
joule - see above
power density - the kevmo is the unit of power density and is 1 watt (or joule) per cubic meter
I don’t think you got it any more than the other guy. He says that 1MW means 1MWH, that it’s a short-handed thing in, well, the coal industry. And all of us should know how the coal industry talks about such short hand because, well, coal used to be delivered by hand to each household or something like that.