Unfortunately that was more a joke than reality. If it could be done we would combine diodes that way all the time. You can do three or four but that’s about the limit. Plus that much power cw would likely melt the end of the fiber
the way it is is done involves very precise expensive combiners.
Lets face it, alot of threads here aren't necessary, but can bloom into entertaining conversation.
Is Styro's laser over kill and insane yes, but i'm sure 99% of us watched it
He always stresses safety, and has all the necessary precautions.
Not many young ones like him have the means nor talent to build this and if he chooses to try and combine these beams, just watch it grow more.