Erm, what? you mean the second video of the guy wearing grey top and black shorts has never been in a fight? explain....
You can do partner shadowboxing. That is, just shadowboxing against another shadow boxing opponent, away at each others' arms length. True that shadowboxing is underrated for many reasons. But that exercise I mention here, got me back into doing it.
THINK SHADOW BOXING REALLY DEVELOPS your balance and how to move and throw at the same time whilst remaining balanced. not many people do that well.
I've been working on shawdowobxing a lot to work on my balance, headmovement and punching while moving. I make sure to do a lot of it with my eyes closed too (I got this idea from scrap). It makes a notciable difference
I guess because it's easier to build speed without the added weight. I've seen plenty of people use those 1Ib wrist weights though.
To be fair, so does the tendency to make short, definitive, but meaningless proclamations like that one.